From Diablo Wiki
Waller is a Boss Modifier found on Champions and Bosses, but not boss' minions, in Diablo III.
One of the more interesting boss affixes in the game, this ability allows monster to create a waist high stone wall that blocks player movement (a few skills can Teleport or Leap over walls) and most projectile attacks. Walls only persist for a few seconds before crumbling to dust, and they can be helpful at times, blocking off enemies from reaching the hero, but more often they are dangerous obstacles that block player movement. They are most dangerous when combined with other boss modifiers such as Arcane Enchanted, Plagued, Desecrator and others that deal high damage and need to be avoided, but even the fact that your player is trapped and unable to escape (in most cases) can be deadly, especially on Inferno.
Waller is one of the few boss mods that differs considerably between Champions and Bosses; Champions can all create Walls, but only short, straight ones. These are always horizontal to the direction of the Champion, and thus if Champions are spread out around the hero, their walls can overlap and form T or + shapes and potentially be nasty traps. Bosses create walls that are like three-sided rectangles, with the open end towards the boss. These trap the hero in a sort of chute that holds them in place and allows an exit only past the boss.
Walls will not appear right on top of a character, so if you are moving around a lot you may see walls appear that have short gaps in them.
- Monster Level Minimum: 10
- Available to: Champions and Bosses, but not boss minions.
- Damage Type: N/A.
- Additional Resistances: None.
Patch v1.0.4 in August 2012 made it so walls will no longer appear directly on top of characters, which could sometimes trap a player.
The Waller mod is a creative one and has unpredictable effects on the battle. It's generally dangerous, as it prevents or limits player movement or escape. This might not matter to a strong melee fighter, but it's often inconvenient or deadly to ranged attackers. Since bosses don't create walls more than about 40 yards away from themselves, ranged attackers can often stay at the edge of the screen and not be trapped by the walls. The real danger is when Waller combines with damaging AoE affixes like Plagued, Molten, Fire Chains, and others, and your character is trapped by walls and destroyed by those other affixes. Waller bosses with Vortex are especially unpleasant for ranged characters, as they get yanked into close range and can not escape.
Walls may also provide barriers to attack, and this is most often seen vs. Champion packs, where all of the Champions are constantly creating short, straight walls, often between themselves and the player. This can be a comical experience in dungeons with narrow hallways, as heroes might need seconds to actually get to the Champions, with them all creating walls that completely block the passage.
 Waller Traps
Player complaints about Waller blocking movement and causing death (when paired with other Boss Affixes such as Arcane Enchanted or Desecrator) were often heard during the first months of Diablo 3. Prompted by these complaints, the developers adjusted the spawning location of the walls to make them (supposedly) not appear on top of players, and not trap players if they did. This bug fix was not entirely successful, and at any rate, players still complained about being trapped by multiple walls cast by champions. This is a feature, not a bug, according to a blue post by Lylirra in April 2013:
In the other, you have walls being spawned directly on top of a character, which basically makes it unable to move in any direction until it despawns — and this is regardless of where the other walls may have spawned, too. This is a bug, because walls should not spawn on top of characters.
Also, I feel it’s worth noting that, while it’s currently the intended behavior for monsters with the Waller affix to be able to spawn tightly near a character, that doesn’t mean the functionality is set in stone forever. We’ve seen a lot of great feedback from players on the affix (like giving walls HP or purposefully staggering where the walls spawn) that we’re definitely reviewing.For the purpose of troubleshooting, though, it’s important for us to identify how the affix is supposed to work right now — what behavior is intended vs. what isn’t — and make that distinction as clear as possible for you. Even if you disagree with how the affix is designed, we still want to be able to fix the bug, and understanding what you’re experiencing (normal mechanics vs. bug) is a key part of that.
 Waller vs. Character Skills
As of v1.08 there is no way to make a wall crumble prematurely (though this is often suggested by players).
Waller is one of the most dangerous boss abilities since not only does it block movement, but it blocks many attacks as well. Characters can use melee attacks to hit targets on the other side of walls, and walls do not block the radius of most attacks or buffs, but most ranged attacks and projectiles are blocked by walls, making them very effective shields against Demon Hunters, and to a lesser extent Wizards and Witch Doctors.
- Compare to the list of skills that can escape the Jailer affix, which controls movement, but does not block attacks.
- Leap will hop over the walls effortlessly. Other movement skills such as Furious Charge will not pass through walls.
- Though the Monk can generally punch enemies on the other side of walls, only Seven Sided Strike will reach further than just past a wall to hit enemies. No Monk skills can move past walls.
- None. Spirit Walk can not pass through the walls.
- Teleport can be used to pass Walls without hindrance.
 Waller Attack Skills
Numerous melee attacks will hit monsters directly on the other side of a single wall, but most projectiles and ranged attacks are blocked by the walls.
 Barbarian Skills
Many Barbarian melee attacks will hit enemies directly on the other side of a wall.
- Ancient Spear and Weapon Throw are blocked by walls.
- Many AoE attacks and effects will work through the walls, including Seismic Slam, Earthquake, Ground Stomp.
- Most Shouts will pass through walls to their usual area of effect, including Threatening Shout, Battle Rage, and War Cry.
 Demon Hunter Skills
The vast majority of Demon Hunter projectile attacks are blocked by walls. Attacks that are stuffed by waller include: Hungering Arrow, Entangling Shot, Grenades, Impale, Rapid Fire, Chakram, Elemental Arrow, Fan of Knives, Spike Trap, Sentry, Strafe, and Multishot.
- The "death from above" rune effects in Cluster Arrow and Rain of Vengeance will pass over walls.
- Bola Shot (projectiles will not pass walls or explode against them, but the radius of the blast from a valid target will extend past the wall.
- The heat-seeking rune effect of Rapid Fire's Fire Support passes over walls.
- Prior to v1.0.3, Evasive Fire shot freely past walls. It no longer does, though from some angles players can get hits diagonally past walls at angles that other projectiles could not.
 Monk Skills
All Monk movement skills and dashing attacks, including Thunderclap, Dashing Strike and Tempest Rush are blocked by Waller, though many Monk melee attacks can hit enemies on the other side of a single wall.
- Deadly Reach's projected waves will pass through walls normally.
- Seven-Sided Strike can not be targeted at enemies across a wall, but those enemies will be hit by the strikes of the SSS if it is cast on a valid target.
- Party buffing or monster debuffing Mantra effects will extend beyond walls.
 Witch Doctor Skills
Witch Doctors fare well against Wallers, since many of their projectiles are thrown in an arc and thus pass over the walls without hindrance.
- Blocked by walls: Poison Dart, Plague of Toads, Firebats, Locust Swarm, Zombie Charger, Wall of Zombies.
- Not blocked by walls: Corpse Spiders, Firebomb, Haunt, the Rain of Toads rune effect in[[[Plague of Toads]], Grasp of the Dead, Spirit Barrage, Acid Cloud.
- The AoE of Soul Harvest, Mass Confusion, and Horrify will extend past walls.
- Sacrifice will detonate Mongrels on the other side of walls.
 Wizard Skills
Most Wizard projectiles are blocked by walls, though summoning attacks and death from above spells can be cast normally over the walls.
- Blocked by walls: Magic Missile, Shock Pulse, Electrocute, Energy Twister, Ray of Frost, Arcane Orb, Disintegrate, Familiar's projectiles, Explosive Blast.
- Not blocked by walls: Spectral Blade, Wave of Force, Hydra (can be summoned past walls, though walls block their shots), Meteor, Blizzard, Arcane Torrent, Frost Nova, Slow Time.
- Archon form can not move through walls, but the Disintegration Wave attack passes through them freely. (While regular Disintegrate does not.)
Excellent demonstration of Waller via a
|Monsters of Diablo III Beasts Beasts: Superunique Demons Demons: Superunique Humans Humans: Superunique Undead Undead: Superunique Objects Bosses Boss Mods Monster Info Fanmade|
Bat - Beast - Blood Hawk - Demonic Hellflyer - Electric Eel - Khazra - Lacuni - Lamprey - Quill Fiend - Rockworm - Sand Monster - Sand Shark - Sand Wasp - Scavenger - Spider - Spiderling - Swarm - Withermoth - Wood Wraith -
|Primary Quest Uniques||
Act One Bosses:
Skeleton King -
The Warden -
Strong CC (Limit 1): Knockback -- Nightmarish -- Vortex -- Jailer
|Act One Uniques||Araneae - Web Spit||Leoric - Summon Skeleton, Teleport Strike, Triple Cleave||The Butcher - Smash, Grappling Hook, Spear, Frenzy Charge|
|Act Two Uniques||Maghda - Forcefield, Summoning Ritual, Punish, Moth Dust, Teleport.||Zoltan Kulle - Fiery Boulder, Time Bubble, Ceiling Collapse, Energy Twister,Vanish, Creepy Laugh||Belial - Phase One: Triple Fireball, Summon Vipers. Phase Two: Poison Meteors, Ground Pound, Lightning Strike, Lightning Breath.|
|Act Three Uniques||Ghom - Acid Slime, Sneeze, Gas Cloud, Chomp.||Siegebreaker - Triple Hit, Charge, Leg Stomp, Grab and Throw.||Cydaea - Pain Bolts, Web Trap, Spider Pits.||Azmodan - Bellyflop, Laser Attack, Falling Corpses, Demon Gate, Pool of Destruction, Globe of Annihilation.|
|Act Four Uniques||Rakanoth - Cleave, Teleport Strike, Blade Strike, Volley, Summon Minion.||Izual - Frost Nova, Frozen, Summon Minions.|| Diablo - Phase One: Claw Rip, Charge, Hell Spikes, Shadow Vanish Grab, Curse of Destruction, Ring of Fire, Ground Stomp, Curse of Anguish, Curse of Hatred. |
Phase Two: Shadow Clone. Phase Three: Overdrive, Lightning Breath.