*Synopsis of the trick.  This is primarily the bare bones of the mechanic.*

*Methods to expand the trick.*

*Reference to other tricks which work well in conjunction with this.*

*Links to builds and discussions*

*Issues that make usage in real games difficult*

*Other important notes*

1. The paragon feat Lasting Frost inflicts vulnerability 5 cold until the end your next turn on a creature you hit with a cold attack.
2. Find some means to ensure your attacks are cold attacks.  Common methods include: using cold powers, dragonbreath manipulation, arcane admixture and frost weapons.
2. Keep dealing cold damage, this is worth 5 extra damage every time you do.

*Wintertouched(heroic feat) grants you CA on cold attacks against creatures vulnerable to cold.  This makes it easier to keep hitting with Lasting Frost attacks, which lets you keep CA…
*Parties with frost attacks can all get the bonuses from a single player with Lasting Frost.
* L12/22 Siberys shard of merciless cold adds a +3/+5 untyped damage bonus to cold attacks
* L11/L21 gloves of ice add a +2/+4 untyped damage bonus to cold attacks
*Winterfury(barbarian PP), Icewrought Sentinel(warden PP) and Winter Sovereign(ED) all have cold-themed abilities.

–Arcane Slashers benefit: the Long Night Scion(warlock PP) feature Winter Winds deals cold damage when you teleport.  It is one of the few means of increasing your slash damage, and generally the easiest.
–Any method of dealing cold damage benefits.  All you need is a small rider of cold damage and you're golden.
–Any means of dealing multiattacks benefits from cold vulnerability, and helps keep it active.  It is as good for damage as any static modifier.

*Links to builds and discussions*

Frost abuse suffers from a common perception of cheesiness.  Some of this is gone now that it's officially confirmed, but the moniker "frostcheese" has stuck.  Some DMs will ban it outright.

Frost weapons have been errataed to remove previous keywords on powers.  This means it's more difficult to stack Frost abuse with other damage types.

1. The Feytouched(warlock PP) feature Slashing Wake deals intmod untyped damage to all enemies adjacent to any square you leave by teleporting.  The Long Night Scion(warlock PP) feature Winter Winds does the same, but is lvl16, deals cold damage and slows those enemies.  A teleport/slashing wake is known as a "slash."
2. From this point, there are two objectives: a)teleport more, and b)improve our slash damage.

1. The Radiant One ED deals intmod extra radiant and fire damage when you deal damage.  This applies to slashes.  Now our slashes benefit from radiant vulnerability.
2. Ethereal Sidestep is an at-will warlock utility that teleports as a move action.
3. Planestrider boots split teleportation powers into 2 smaller teleports, which doubles our slashes from each such power.
4. The Eldritch Panoply set bonus 1 lets us teleport on a minor action after using a teleport power.
5. Shadowrift Blades grant a teleport(split with boots) when we hit a target, in exchange for taking damage.  5 damage for the offhand +3 blade is easily offset by a Ring of Free Time(resist 5 all).  Dual wielding is possible, but exposes a lot more damage.
6.  The Staff of the Traveller(phb3) lets us teleport when we would shift.  Such builds can be called Shift Slashers

–Radiant Abuse will improve our slashes.
–Frost Abuse will also improve our slashes.
–Many arcane slashers are hybrid Warlock|Swordmages, and thus can benefit from catch-22 setups with White Lotus Master Riposte and Aegis of Assault.  Aegis of Assault can be split, giving a damage match with White Lotus Riposte.
–Dancing Weapons give a higher chance of applying frost abuse, let us trigger shadowrift blades more, and let us use the Ring of Free Time's post-milestone benefit(extra minor action each round).
–Eldritch Strike is a warlock at-will usable as an mba, and so we can benefit from charging, and any arcane benefits like arcane admixture.
–Feycharging meshes almost perfectly with Slashing.

Arcane Slasher by AlphatheGreat
Nightcrawler, a Shift Slasher by AlphatheGreat

*The basic mechanic of the slasher is very difficult to challenge.  Slashing Wake and Radiant One are both very well-defined and rarely challenged mechanics.  Radiant One is Dragon material, though, as is Long Night Scion.  Hybrids are often needed to reach the build's full potential, which can cause some sticking points with DMs as well.
*A slasher's biggest challenge is finding a consistent way to apply radiant vulnerability.  Some of these methods are sketchier than others.  Which you use determines a lot about the build, and about how acceptable it will be to your DM.
*Getting multiple attacks is often one of the most important means of increasing a Slasher's damage, and can involve all sorts of modules that DMs will challenge(like catch-22s or spending all your daily item usages on Dancing Weapons to have one active all the time)

*Other important notes*

1. Find some source of improved crit range (several feats, PPs, or powers offer expanded crit ranges).
     a. Student of Caiphon works for locks.
     b. Daggermaster is a popular option (especially for sorcerers).
     c. Raise the Stakes (rogue power) works if crit-fishing for a small window.
     d. Chosen of Erathis' Anthem of Progress works fantastically for one encounter/day.
     e.  This is not a comprehensive list…
2. Find some means to effectively reroll attacks.  Rerolls are important because combined with expanded crit range, they greatly increase critical range.
     a. Averger's Oath of Enmity
     b. Sorcerous Flux feat (assuming you hit multiple targets, the roll swap is effectively a reroll).
     c. Sage of Ages lvl 24 ability (works as a reroll 1x/turn).
     d. Again not comprehensive…
3. Stack effects that proc on a crit.

–There are several ways to gain extra attacks on a crit (Ruthless spellfury, Rending Weapon, Two weapon opening just to name a few).  note: you now only get 1 free action attack per turn.  Some crit-activated attacks are free actions, some are not.  Make sure you know which are which.
–Storm Sorcerers in particular benefit from crit fishing as Fury of the Storm maximizes extra damage dice they get from crits.
–Dice of Auspicious Fortune are very abusable with this combo when you have "rest days."

Example build: Storm Sorcerer (not up to date, but give the general idea).

Potentially broken when used to generate near guaranteed crits, but the concept itself is simply a way to increase DPR (and crit related effects).

1. Arcane at-will attack, preferably one that can be used as a melee basic attack
2. Aegis of Assault or some mark which is enforced with an attack or lots of damage near that of your arcane attack which can be administered/sustained outside of your arcane attack
3. White lotus Riposte + White lotus master riposte

Power of Arcane semi-controversially makes associated powers arcane
Charging Aegis(swordmage epic feat) allows you to mark on a charge, eliminating the need to stop to mark your target.
*Eldritch Strike+White Lotus Master Riposte+Deadly Draw+Boots of the Adept Charger(or Avalanche Boots)+Polearm Gamble will likewise accomplish the "hit me and hurt" half of the catch-22.  Eldritch Strike your opponent, sliding them to get CA.  Then shift back one.  If they come after you, polearm gamble triggers and you hit them again.  WLMR may not be needed in this case.

*Any build that gets increasing returns off hitting, like the Arcane Slasher, will benefit from the Catch-22
*Arcane Slashers, Feychargers, and any Assault Swordmage build can see impressive dpr numbers come from this.
*Frost Abuse. Because of the arcane at-will requirement, White Lotus Master Riposte will always work with Arcane Admixture to add cold to the attack.

Many DM's won't like the catch 22

*Need to be within 2 to mark with aegis.  Monster dies and you must be near your next target to ensure it. 
*There are other means of ensuring a catch-22, like Hellish Rebuke.  If/when they get added, I will remove this note  -Alpha

1. The Ancient Soul feat allows players to recharge their Dragon Breath power when they take damage of the same type as their Dragon Breath.
     *Note: There are other ways to recharge Dragon Breath, but this is the most reliable.
2. Their are several ways to self-inflict elemental damage.
     a. Lightning Strike does DEX mod lightning dmg to a secondary target (questionable if this works because of targeting rules though).
     b. Skull-taker's Rage power works if used with a weapon that grants the appropriate elemental key word.
     c. Delbanian Vambraces (lvl 23 item) work for Cold Breath
     d. Including one's self in the AoE may work (and may kill you).

–Ninefold Master makes Dragon Breath an arcane power belonging to all of your arcane classes and Arcane Sword's capstone makes a swordmage encounter attack power an at-will power (read: Dragon Breath is now an at-will, minor action attack power).
–The Dragon Breath power has a fair bit of support through feats, items, etc.

Example build:

–Used with the Swordmage Capstone this combo is broken, but then again it only functions as a lvl 30 build.
–Use of Lightning Strike is (as noted above) debatable.
–In general, pretty cheesy as it gives a free AoE attack as a minor action at least 1x/round, on top of whatever standard action the character would normally take.

-Paragon level, fighter class (base or via MC), 15 wis and 15 dex

 

-At-will push/pull/slide of 2 (usually achieved by getting a push/slide of 1 and wearing rushing cleats) using a polearm or spear.

 

-Polearm Momentum feat

 

Result: ability to forced-move and prone at will

The real trick to this is getting the at-will forced movement.  Viable ways to achieve this include:

 

– being a half-elf and taking Eldritch Strike as your dilletente power (popular for chaladins)

 

– Mark of Storms and some way to use lightning or thunder powers at-will

 

– being a half-elf or a barbarian and taking pressing strike

 

– being a predator druid (alfsair spear) with Savage Rend and/or thorn strike

 

– taking the warden PP that lets you slide on primal powers with the frost keyword, and taking a frost at-will

 

– taking the Ardent PP that lets you slide on powers with the fear keyword, and acquiring a fear at-will

 

– there is an epic-level feat (17 con requirement) that allows you to push 1 with opportunity attacks with axes whether you hit or miss (you'd be using a halberd in this case)

– If the at-will that you use is a melee weapon at-will, then wielding a glaive and having 15 str will mean that you can take Heavy Blade Opportunity and do this on opportunity attacks.

 

– If the at-will is an MBA, you can use it on opportunity attacks, charges, and other granted MBAs.  This gives additional control to the party attack-granter (if any) and is really quite useful with the fighter CC or the Polearm Master mark-punishment path feature.  Note that immediate interrupt mark-punisments can actually prevent the enemy from making the attack that triggered the punishment.

 

– If either of the previous two is true, and you have 15 str, you can take Polearm Gamble, allowing you to do this on enemies who move adjacent to you.  It also synergizes well with any sources of threatening reach you might have.  The Polearm Gamble version works *particularly* well with the epic-level feat, though by this point you have to have at least 15 in str/wis/dex and 17 in con, so it's a bit MAD

 

– any version that uses this as an opportunity attack/punishment attack will benefit in the obvious ways from opportunity attack and punishment attack optimization.

 

– For those using Mark of Storms or the Warden PP, it is entirely possible to construct your character so that *all* attacks are of the appropriate element, which means that you get to stack the slide/knockdown on everything you do.

 

– Even for those not using MoS/the Warden PP, any additional powers that you pick up along the way that push/pull/slide will be augmented appropriately.

 

– There are MAD issues, but the Iron Vanguard fighter PP deals additional damage equal to your con mod every time you push, slide or knock down an enemy.  Draconic Arrogance (Dragonborn feat) deals additional damage equal to your str whenever you push or knock down an enemy.

 

–If you can slide on a basic attack(as with Eldritch Strike), polearm gamble can stop enemies without reach from moving adjacent without shifting or teleporting; any hit with an OA as they approach will leave them prone and nonadjacent.

 

–Rushing Cleats can be used to boost pushes and slides from close or melee attacks.

 

–Ring of the Ram and Ramming Gauntlets can boost pushes.

 

–Spear Push will boost a push from a spear or polearm.

 

 

– As always, knocking prone synergizes well with the dazed condition.

 

– The heavy forced movement aspect of the builds that take advantage of this synergize well with zones, area attack powers, and damaging terrain.  The knockdown can make it harder to leave – particularly if you can use the PG trick to block off exits.

 

– The forced movement + knockdown works well with sources of difficult terrain, the slow condition, and things like gloves of antipathy – when used properly together they can render melee enemies unable to actually reach any targets for a round or so.

 

– Prone is an easy source of melee CA, and there are a number of items and builds that do additional damage with CA.  This will not be of use to you so much, but can be of great help to your allies.

 

– The warden PP gets the obvious cold synergies.  The MoS version (often casters with Arcane Implement Proficiency: Heavy Blade and area effect powers) get the obvious thunder synergies.

 

– For Chaladins, this synergizes *extremely* well with the Polearm Master double-punishment trick (divine challenge an enemy and stand near him.  If he attacks a friend, you get your DC autodamage and your Polearm Master punishment attack)

Polearm Warlock: community.wizards.com/go/thread/view/758…

–Some DMs will object to using implements to trigger the feat.

 

–Some DMs might not allow things like the slide from Mark of Storms to count as part of the power, treating it as a different effect that did not come from a polearm attack

 

–The power of the combo appears cheesy, but remember that it comes at a cost, dominating a large number of feat choices and making for a very MAD build.  Threatening reach makes it worse, but has limited availability.  Nevertheless, some DMs will have a knee-jerk "nerf!" reaction.

Only slides from an attack with the weapon count; slides that do not come from an attack will not.

Cause an enemy to lose his action by moving him based on immediate interrupts and opportunity attacks.  Most of these techniques work with the fighter class through the Combat Challenge class feature, for denying attacks, and the Combat Superiority feature, for going beyond stopping movement on opportunity attacks.  There are a few ways to get this:

• Lashing Flail (Combat Challenge and Opportunity Attacks)
• Mark of Storm and Lightning Weapon (Combat Challenge and Opportunity Attacks)
• Shield Push (Combat Challenge)
• Forceful Opportunist (Opportunity Attacks, requires Fighter Weapon Talent)
• Swift Spear (Opportunity Attacks)
• Heavy Blade Opportunity and attacks that push or slide (Opportunity Attacks)
• Goad of Blood and at-wills that push or slide (Combat Challenge and Opportunity Attacks)
• Savage Rend (Combat Challenge And Opportunity Attacks; requires multiclass Druid, hybrid Druid, or Half-elf dilettante)
• Knock-Back Swing (Opportunity Attacks)
• Battle Awareness feat power (like Combat Challenge, 1/encounter)

 

                                

• Staggering weapons extend slides by a considerable amount.
• Rushing Cleats and Ring of Ramming extend pushes.
• The Whip, Spiked Chain, and Triple-Headed Flail are Superior flails that grant a +3 proficiency bonus.
• The Devoted Challenge feat gives dwarves an excellent bonus to their Combat Challenge melee basic attack.
• The Polearm Master feature Longarm Grip grants melee basic attacks on those who violate marks within reach.  This applies to the main-hand end of a Spiked Chain, since it bears the Stout property.
• The Chain Ward feat power and the Reaching Stance paragon path power from Polearm Master let you negate and slide with reach against opportunity attacks.

 

                                

• Polearm Abuse, if you're using a Polearm for your weapon
• Lightning/Thunder Twinking, with the Mark of Storm

 

No builds that I know of.  A Dwarf weapon talent flail fighter with Devoted Challenge, Lashing Flail, Weapon Proficiency (Triple-Headed Flail), Armor Proficiency (Plate), a heavy shield, and the Pit Fighter paragon path would be a fine fighter indeed.  One could combine this with Staggering Challenge to put an opponent in a very bad position.

                                

• Reach on monsters can be a real issue.  The denial doesn't happen if you can't move the opponent out of reach of your ally.  Rushing Cleats and Staggering weapons can extend the slide, if necessary.
• You need to position yourself well such that your mark can be enforced with the denial, and you need to push or slide creatures in to an appropriate position.  For instance, if you enforce your mark on a shift, you need to position the opponent so that they cannot charge your ally without retribution.
• If you consistently deny attacks to your DM, he won't bother attacking anyone but you.  On one hand, this means you're doing your job.  On the other hand, make sure your defenses are good enough to take the abuse.
• The two methods for movement on both combat challenge and opportunity attacks have some trade-offs:                                    
  • Lashing Flail                                    
    • Advantage: works for both Combat Challenge and Opportunity Attacks
    • Disadvantage: doesn't work until paragon
    • Disadvantage: you have to use a flail, which otherwise doesn't have a lot of support

     

  • Mark of Storm and Lightning Weapon                                    
    • Advantage: works for both Combat Challenge and Opportunity Attacks
    • Advantage: synergizes with Lightning/Thunder Twinking
    • Disadvantage: requires a Dragonmark feat, so you need DM approval or the Eberron setting and it excludes taking the Mark of Warding feat
    • Disadvantage: requires an expensive weapon

     

   

 

This list is not exhaustive. 

This is the combination of radiant vulnerability, feats and items that augment radiant damage, and a source of constant radiant damage.  This works best when many part members have sources of radiant damage (thus the "Mafia"), but a single character can use it as well.

*For classes that don't have enough radiant powers, you need a weaplement that converts or adds radiant damage.  These include the Crusader's Weapon, Sunblade, Brilliant Energy Weapon, and Radiant Weapon.  The Sun Disk of Pelor also works (e.g. for hybrids).
*The Radiant Weapon does extra damage with radiant damage.
*The Crusader's Weapon converts only half of the damage to radiant, allowing you to use another damage-type module (such as frostcheese) in addition.
*The most popular ways of adding radiant vulnerability are: Channel Divinity: Solar Enemy, Power of the Sun, and Morninglord.
*The following improve radiant attacks: Radiant Servant, Student of Caiphon, Nimbus of Light, Clinging Radiance, Invoker's Blaze, Radiant Vessel, Punishing Radiance, Radiant Advantage, Font of Radiance, Radiant Power, Torm's Radiance, Astral Holy Symbol, Ring of the Radiant Storm
*Pervasive light allows you to exploit radiant vulnerability even when not doing radiant damage, again allowing you to use another damage-type module.

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Doing so isn't hard – just take the Familiar Mount ritual. It's cheap and casts fast. For best results, pick a familiar with a special movement mode, such as flying.

– Wizards who take the utility power Familiar Harrier and equip their familiar with a Nightmare Saddle gain a teleport speed of 10.
– For non-Wizards, the feat Space Bending Familiar gives you a teleport speed of 2 when combined with Nightmare Saddle.
– Taking the Active Familiar feat nearly doubles your mobility.
– Giving your familiar a Charm of Protection keeps it safe longer and doesn't take up the same item slot as Nightmare Saddle.
– Especially good familiars are Specter, who does not provoke OAs, and Gelatinous Cube, who has permanent invisibility, keeping him in the rodeo for much longer than your average familiar.

Familiar Mounts can be easily incorporated into any Arcane build that has a few feats to spare.

The Blade Dragoon, by Adslahnit

These options combine in an obvious and predictable way. They're incredibly fun without being overpowered. I don't see any DM banning this.

– Familiar Mounts increase your mobility, but if they die you're SoL for the rest of the encounter.
– Non Arcane classes can use this trick by MCing into an arcane class and picking up Ritual Caster if they don't already have it.

Charge via Fey Charge, using various feats/features/powers that assume Fey Step is an encounter power (most noteably and almost required, Eladrin Swordmage Advance).  Hit (required), keep Fey Step via Fey Charge, and repeat next turn

 

• Planestrider Boots, to split your teleport in half and hopefully proc ESA a second time.
• Round About Charge, for easier charging
• Other general At-Will optimization, cause you'll take lots of them
• Potions of Clarity, Sage of Ages and Martial Supremacy to not ever miss (because then Fey Step is expended and the ride ends)

 

 

• Arcane Slashing (you teleport a lot…)
• Catch-22 (you're already a swordmage)
• Charging (You charge every turn)
• Critfishing (3-4 attacks a turn, so crits will happen.  But the charge has to hit, so don't tank accuracy)
• Frost Abuse (CA helps to hit, 3-4 attacks amplify static damage)
• Radiant Mafia
• more

 

The originating thread, SongNSilence

Rather non-cheesy for something that enables 1k-DPR builds.  Expect to be nerfed though, if not by your DM, then by future updates.

Used with discretion, feycharging is often a great answer to bumping the damage of a swordmage in paragon.  Don't give the DM a reason to hate you, and your party will love you.

Charge.  The +1 to hit is always good, and then through stacking feats and Equipment, your basic at-will can be competitive with encounter powers.

 

• Equipment                  
  • Vanguard Weapon (+1d8 on charges, cheesy usage in off-hand)
  • Avalanche Hammer (+1[W] on charges)
  • Horned Helm (+tier d6 bonus damage on charges)
  • Badge of the Berserker (neck slot, charging no longer provokes OAs)
  • Boots of Adept Charging (shift 1 after a charge helps reduce foe's options)
  • Lancing Gloves
  • Impaling Spear (further help accuracy with all the basic attacks you make)

   

• Powers                  
  • Eldritch Strike (slide 1 helps reduce foe's options, counts as a basic attack for everything)
  • Howling Strike (bonus damage on charge)
  • Maurader's Rush (bonus damage on charge)
  • Throw and Stab (bonus attack before charge)

   

• Feats                  
  • Surprising Charge (+1[W] if charge with CA)
  • Fey Charge (…)
  • Powerful Charge
  • Mounted Combat (nice heroic mounts found in the heroic section in the DPR king candidates)
  • Barreling Charge
  • Roundabout Charge
  • Draconic Arrogance: like Iron Vanguard, but keyed off strength

   

 

 

• Catch-22 (Good MBA required)
• Feycharging
• Broom Builds (prone foes have even less options)
• Frost Cheese (Surprising Charge works especially well with constant CA)

 

 

• The San Diego Super Charger

 

The only cheesy bit listed here is wielding a Vanguard Weapon in your off hand.

It can be rather equipment dependent.

A revenant with fierce vitality, or a barbarian with enduring rage won't fall unconscious below zero hitpoints. Make sure to autosucceed the death save (life charm to take 10, or PP/item combination to get to 20 to use a healing surge). This effectively adds +50% hitpoints, but the real benefits lie in the expanisons…

Below zero benefits:
revenant(shadar kai) + deathless warrior: reduce damage by 5+conmod
revenant + ghostly vitality: gain insubstantial
=> combine with ring of free time, assuming con 28
effective DR: 38

addon: rogue with cunning sneak and sehaines mark of dark moon
effective DR: 76

and anything that makes you even tougher (battlerager, swarm druid…)

Undying
ED: Raven consort:  get the effects of a healing surge without spending one by rolling 20+ on death save (easy with PP and some items)
=> enemies must reduce you below negative bloodied, breaking a DR of 76, in one turn – otherwise, you return to positive + HS value.

Mark of Storms Feat+ either/or Genasi/Shocking Flames feat or Lighting weapon +(optional) Rushing Cleats or Battering Shield

Turns all of your melee attacks or weapon implement attacks into slide attacks. Take advantage of zones, conjurations, and terrain features. Also has great synergies with slowing or Immobilizing attacks.

-Great synergy with Polearm Trick, especially polearm momentum/gamble. Hit them before they get to you and slide them away and prone. Use with cleats to obtain slide 2.
-Also good synergy with any bonus OAs, especially if you have Hindering shield and Battering shield to slide away and slow. If you are Warden…well you can also get turn the slow from hindering into daze to leave them both moved away and dazed, paired well with
-Don't forget Ebberron Shard of lighting, also Take advantage of PPs and Destinies that enjoy usage of slide or lighting damage

Links to builds and discussions

It's not crazy broken but still same issue as frost cheese where you are very dependent on lightning damage. Also Need to ask DM about using Dragonmarks outside of an Ebberon Campaign, without the Mark of Storms, trick falls apart. 

Mark of Storms only activates on lighting attacks, cleats only activates on closed/melee attacks

Master's Surge (acadamy master PP) + Archspell (Archmage ED) + Visions of Wrath (Wizard 29).  Have low Int (13 @ 21 for MC wizard) and cast bare handed.  You should then only hit on a natrual 20.  When you miss, the enemies will then be stunned (save ends) and you don't expend your power.

Sorcerer can make good use of the PP and ED till lvl 30.  Add a few re-roll powers and daily recharge (Archmage has 2 recharges) in case you roll a 20.

Spell Focus or other save end penalties can also be usefull for letting you do other attacks.  A high init would esnure the enemey doesn't get any turn.

Not letting enemies have a turn can really take the fun out of things.

Only works at lvl 30

If you play a stealth centered character, you want to make your you always can hide. The problem is that you cannot always rely on a favourable battlefield for that.

But there is one source of full cover (at least three line of sight blocking corners) you always have – your allies. The problem is while you can hide behind a creature, you cannot stay hidden behind one… as long as you don't have other ways of maintaining at least cover or concealment.
Also having permanent concealment is cool, because it gives you +2 vs melee and ranged attacks.

The most commonly known ways to get cover is the Warlock's Shadow Walk or certain items like the high level Ring of Shadows.
One way is open to everybody, thogh… You first have to get an Enshrouding Candle (level 7 Woundrous Item) to wear, say as a Necklace – that turns every square within 2 into dim light. Now you MC (or Hybrid or are) into Assassin and pick up Drawn Shadows as feat at Paragon – congratulations, you have permanent concealment now ! The best is Shadow Step let's to teleport right there, in case you're tangled up in melee, and the MC Assassin feat also gives you training in stealth.
At last you might want to pick up an item to boost your stealth – there are plenty of item bonuses, and Assassin's Armor lets you roll twice for stealth. You also might want to pick up Skill Focus or Secret Stride if you rely heavily on stealth.

— If you're hidden mobs will have hard time targetting you !
— You also get easy CA… even for melee attacks if they include a movement part, like the Rogue's Deft Strike or the common charge.
— Certain Paragon Paths Darkstrider or Champion of the Vigil and some other features rely on you being hidden.

— none —

Medium.
The stealth rules are explicit that cover from creatures only doesn't help at staying stealthed, but doesn't forbid stealthing in their full cover itself – but your DM might not draw such a fine distinction…

Don't try that as Plate wearing Dwarven Fighter…