Broken/Bent fixed by Errata
Bag of Rats of HealingAssured Healing gives a small amount of healing when you miss with a divine attack with the healing keyword. It's a fairly small amount of healing, and it requires attacks, so that's not that easy to break.
But Astral Seal is an attack that does no damage and has the healing keyword, so it's safe to use your your allies out of combat. Now, odds are your allies would rather not get hit by each other, so it would be better if you miss. Ok, don't use an implement, close your eyes, have your ally go prone, behind cover. Heal the whole party.
Found by brc
Fixed By: The Rules Compendium definition of a Legitimate Target (p.108) does not include your allies. The original DMG defintion of the Bag of Rats rule only limited effects triggered from hits, but the RC version applies to miss effects as well.
Blade CascadeArrange things so you only miss on a 1, and get lots of rerolls to reduce that probability. Lots of static damage modifiers, go kill something.
Fixed by errata. Blade Cascade (Ranger Lvl 15) is currently capped at 5 attacks.
Bloodpulse + Bolstering Blood + Forced movementBoost Blood Pulse with Bolstering Blood, and then push. (1d6+2d10)*squares moved. The March 2010 update changed it to 5 points of damage per square voluntarily moved, which made it completely useless.
Combat cast Imprison RitualUse the Magister level 30 feature Magic's Master to cast the Imprisonment ritual as a standard action, after you've used Orbizard tricks to guarantee someone's unconscious for at least 1 round. Tack on Ancestral Incarnate (or Visanti feats) to help manage the costs.
Fixed in the May 2010 Update by requiring the ritual not target an enemy.
Source: Found by Sven Stryker
Create a Target(MP2) + Forced MovementHit with Create a Target. Hey, Overwhelming Strike has forced movement, and can be an MBA. Avenger: Overwhelming strike. Add potions of clarity and leader buffs to move this into "Infinite attacks: Infinite damage"
The May 2010 update made the attack an opportunity action.
Demigod or Chosen, Divine MiracleAllows for infinite damage:
All of these except Trip Up were fixed in January 2010's update by changing Demigod's level 30 feature to only refresh Attack powers. The March 2010 update picked up Chosen, and then further limited Divine Miracle to once per encounter to cover Trip Up
Dual Earth Brute Ping-pongInfinite damage . Summon 2 earth brutes (Salve of Power, Action Point), and place the victim between them so that he bounces back and forth, dying from the 5 damage.
The May 2010 update added "Willingly", so it no longer recurses.
Follow-up Blow and Wicked StrikeInfinite attack loop. Follow-up Blow allows you to make a melee-basic attack when you hit with a power that is not a melee-basic attack. When you make the MBA, replace it with Wicked Strike, relying on the "in place of" language to allow you to use it as your attack, while keeping it from "counting as" an MBA.
The May 2010 update limited Follow-up Blow to once a turn, which really took out the Nova potential.
Harmonious Thunder (PHB3, Monk Daily 1)When one of the targets takes damage, the other takes thunder damage equal to your Strength modifier. Doesn't that trigger itself?
The July 2010 update limited it to once/turn
Heavy Blade Two-Weapon Flurrying Opportunity of DeathWield a heavy blade in each hand (Drow Throwing Knife if you're not a Two Weapon Ranger). Have the Two Weapon Flurry feat, and the Heavy Blade Opportunity Feat, and know Twin Strike as an At-Will power.
Monster provokes Opportunity Attack. Use Twin Strike to make it... if you hit (likely, two attacks), then you get an opportunity attack with your off-hand. Instead, use HBO to sub in Twin Strike, at a -5 penalty. Hit, repeat. The penalty shouldn't grow, because it's from one element and thus doesn't stack... so as long as you can keep hitting at a -5 penalty, you'll keep attacking.
Fixed By: Feb 2012 update made it an explicit free action.
Inevitable Sucking (Inevitable Accuracy + Grazing Shot)Using Inevitable Accuracy, you can keep making basic ranged attacks until you hit. Using Grazing Shot, your misses do damage. So ... um ... find two targets you can attack, suck at your ranged attacks, and don't hit. Add rerolls to avoid 20s, and kill anyone.
Found by Kerbarian
Fixed by the July 2010 update that limited you to one free action attack/turn.
Nasty Sucking Backswing (Nasty Backswing + Scimitar Dance + Reliable Encounter powers)Use the level 30 features of either Glorious Spirit or Heir of Siberys to effectively make some free action encounter attack power reliable. I recommend Nasty Backswing(Rogue). Add damage-on-a-miss (Scimitar Dance, Versatile Duelist to make it a rogue weapon), and start the sucking.
For additional reliability, be an Avenger as your primary class, take Serene Initiate as your PP, and choose the lower die from Oath of Enmity. That should kill most anything before the double 20s show up.
Found by Kerrgma
Fixed by the July 2010 update that limited you to one free action attack/turn.
OrbizardThe name comes from an Orb focused wizard, but the trick is actually about stacking penalties to saving throws, and can currently be done by a large variety of base classes. In fact, while the Wizard version has been fixed by the March 2010 update, the Avenger version still lives, I believe.
Give someone a save-ends stun or similar "you no longer matter" condition, with a -16 penalty to their save. Current example build. Still need original source (Elven Orbizard Demigod)
Build elements used
The November 2009 update made it much harder to pull of, but it's was still possible for an Elven or Deva Orb Wizard. The March 2010 update changed the base Orb of Imposition power, and thus made it pretty much worthless to focus on save-ends powers for everyone except certain avengers.
Kiss of Death (MP2)Allows for Infinite damage to one monster. Since the free attack from the stance triggers the stance, just don't miss. Or use a mace and Hammer Rhythm, and just plain do infinite damage.
The May 2010 Update made this an opportunity action.
Large MultiattackThe March 2010 Update hammered ways of getting extra actions, the May 2010 Update hammered Follow-up blow, and the July 2010 Update stopped crit-recursion.
Sources of Extra Actions
Large Damage Bonuses
Large Attack Bonuses
Orb of Temporal DissonanceYou've got a party with a Tac-Lord who's both invested in Init boosters for the party, and has Strategist's Epiphany?, well then, pick up this orb.
When the Tac-Lord pulls out his "I rolled a 60 on my history check, Team PC goes first" routine, delay to the end of Team PC. Then use the Orb's daily. On the rerolls, everyone's going to get a lower result, so now everyone on team PC gets to go again, and will still likely go before the monsters. Two turns before team monster, great for eliminating team monster before they ever go.
Fixed By: May 2011 update, which changed it to a "Team PC bombed their init checks. Reroll them" item. Strategist's Epiphany was also fixed.
Punisher of the Gods, Immortal Curse
The first one was fixed by a changes to Dual-Strike and Rain of Blows which eliminated two of the extra crit-provided attacks, which causes the chain to decay quickly. The other two were fixed by the RRoT July 09 errata which eliminated the critical hit language.
And then PotG was fixed in republication in the Dragon Annual to only give an at-will attack instead of an action point, and only once a round.
Brutal Radiant Slides of DeathRadiant Ones Starborn feature adds a fair chunk of damage to all your damage. Not damage sources, not hits, just "Whenever you deal damage to a target that is granting combat advantage to you".
Let's see how we can abuse that. Obviously, we'll need to apply a radiant vulnerability. Let's use Morninglord. Now we're doing 10+Int extra damage to every damage source we have. Now, how can we get as many damage sources as possible?
Spark Slippers! If you can slide someone each time you hit them adjacent to you, that's 10+Int damage each time. A long slide can become adjacent to you multiple times, if you're willing for your DM to beat you.
Mark of Storms to start the slide, other equipment to continue it, and you can get up to 10 squares of sliding, enough for at least 5 doses of adjacency damage. Per hit. Now, how to get more hits?
Source: langeweile pulled this out to develop the BB/BR combo
Fixed By: Spark Slippers were nerfed in the June 2011 update. They are now just once a turn, leaving a traditional ~300 DPR BB/BR spamming battlemind.
Relentless Assault & High Crit Range partiesDo you have a party that can all make basic attacks? Throw down Anthem of Progress and follow it up with Relentless Assault. With only 3 people who can attack (critting on 16+ thanks to Anthem of Progress), each crit will generate another crit on average. With more, it rapidly explodes. Add Avengers or Dice of Auspicious Fortune to taste.
Fixed in October 2009 by making the generated attack an opportunity action.
Zone Ping-PontSet up two "damage on enter" zones, and then add in some effect to allow you to recursively move a target between them. Alternately for DPR instead of breaking things, just have staggering weapon and move a target in/out of a zone lots/hit.
Fixed in Jan 2012 by the global zone 1/turn nerf. Actually still broken as of the end of Jan one from a couple of specific zones that were missed, but generally much harder to pull off.
Rod of Reaving + Rod of Corruption kills all minionsKill all minions on the board as a minor: Curse one. It dies due to Reaving. Curse to others via Corruption. They also die from Reaving. I don't know the original source. Please help. Linking makeshiftwing's thread for now.
The November 2009 errata fixed Rod of Reaving to only work on non-minions.
Scion of World EndingScion of Sacrifice has a level 16 feature to allow you to use an at-will power whenever you drop below zero. You know that's gonna be trouble. Attack yourself (Throw and Stab, or various AoE at-will powers have been suggested), have enough resistance that you will kill yourself very very slowly, some way of healing regularly (like a staff that heals you when you kill a monster), add something else to move around a lot (Mobile Warrior), and destroy the world.
The July 2012 update make it a free action.
Found by Mellored, Monkeygentlemen, Nelphine, ThatWasTotallyNinja, and the rest of the hive mind
Super-critical recursive criticalsIf you can cause one critical hit to create 21 attacks, odds are that one of those 21 attacks will be a critical. If that critical spawns another 21 attacks, then the odds are pretty good that your setup will "go critical" and never end. That's ... not going to happen. But if you increase your crit range, the target number of rolls drops.
Getting rerolls will have a similar effect, although not quite as potent. If each critical spawns a single attack with 21 rerolls, you'll probably get a few cycles in... but eventually you'll get unlucky and the cycle will die out.
Here's a table with some examples that would usually go supercritical. I only have currently legal examples of the 16/2/4 line.
For the generic case, you need the result of "n*(1-(1-c)^r)" to exceed 1, where n is the number of attacks, c is the chance of a crit per die, and r is the number of rerolls.
Reckless Attacker was changed to once/round, and Punisher of the Gods was changed to no longer grant action points.
Salves of Power no longer can refresh Bless Weapon, which broke SanityFaerie's build.
And then the July 2010 update fixed the class by limiting free attacks to 1/turn.
Threatening Strike(DP) + Forced MovementHit with Threatening Strike. Until the next turn, you get a free MBA when the target moves. Forced movement counts. Hey, Overwhelming Strike has forced movement, and can be an MBA. Action Point: Overwhelming strike. Add potions of clarity and leader buffs to move this into "Infinite attacks: Infinite damage"
The May 2010 Update made the teleport an Opportunity Action.
The infinitely brutal Vorpal GlaiveInfinite damage 1 round/encounter. ( Ishi)
Three battle engineers all use Greater Magic Weapon to make the glaive brutal 3 (or the Falchion, or if you have more battle engineers, any other weapon). On a hit, all dice are 4s and are thus rerolled.
The November 2009 errata changed the text to disable brutal stacking, and thus stopped this issue.
Warmaster + Horizon WalkerInfinite actions each round for the rest of the party. You spend your action point to take a move action, get it back, repeat until bored. Each AP you spend gives a free action to an ally. Or find a way to attack as a move action (Quicksilver Stance used to work, but got Errated) and have infinite attacks by yourself.
The November 2009 errata completely changed the Horizon Walkers action point feature, breaking this loop.
"Overpowered" things nerfed by update
Both were frequently used in large multiattack nova builds to escape action economy limits. The March 2010 update heavily nerfed both... although I'm not sure the Boots of Eagerness nerf actually changed anything.
Cheap Magic ItemsHave much more magic than expected. Use the Ritualist's Ring and the Lorekeeper Destiny to make magic items cheap, then buy a lot of them. TD complained about this rather loudly.
Fixed in the November 2009 errata. Both Ritualist's Ring and Lorekeeper's Cunning work on only non-creation rituals now.
SlashingMake your teleports hurt people you teleport next to, and then stack damage types and vulnerabilities until elder deities explode when you teleport by.
Ways to make your teleports hurt
Source: Alpha the White's Arcane Slasher thread.
The July 2010 update limited most sources of slashing damage to 1/turn.
Surgeless healingLots here. I'll let others enter them.
Clerics only add Healer's Lore to powers that spend a surge after the May 2010 Update
War Wizard's Travel CompanyCreate a zone of autodamage, and use a close arcane attack of your choice through a staff. Via War Wizard's Staff, slide the target a completely undefined route through the damage-zone multiple times until it dies, finishing with the corpse ending up in a square adjacent to you.
Fixed by the mass update of damage zones, and then the July 2012 fix of Lightning Fury
Found by Mellored
Suggested House Rule: "you can slide one adjacent creature directly to a different square adjacent to you". And also rule all autodamage sources 1/turn.