The Dread Vault

Description
Mind Flayers have heard the call of the ancient elder brain and now toil to release it from its prison. Stop them before the elder brain can rise to power!

Bosses of The Dread Vault
Basic Strategy: The best strategy is to quickly burn the adds and avoid directly attacking the boss as much as possible. A rather involved fight, but manageable, provided you remember two things: (1) stay AWAY from the tentacles; (2) knockback skills will save your bacon. Bull's Charge is especially effective. Stage One Once the party spawns in the boss arena, ignore the adds and beeline for the back left corner of the arena, behind Yshiggol, taking particular care to avoid the many tentacles in the area. If one hits you, it will do 8-10k damage and knock you prone long enough for the tentacle to hit you again--rinse, repeat. The end result is almost certainly death, and will probably cause the death of anyone who tries to revive you. Also, if you die, you're out of the battle, as you revive in a penalty box until the party wipes or they manage to beat the boss without you. Since this fight can take 15-30 minutes, you should probably keep a good book handy. Once you've reached the safe area (it's the raised area in the back out of range of the tentacles), where you will spend the rest of the fight, you'll be swarmed by the adds you avoided attacking on the way, a mix of Mind Flayer Scourges, Mind Flayer Infiltrators, and Ustilagors. Nothing too terrible, but there will be a bunch of them. Also, you can use this opportunity to practice Add Pinball (i.e., using knockback to send mobs over the edge of the arena) to clear them quickly. Eventually, you should be down to 1-3 Ustilagors, which respawn constantly during the fight. At this stage, you can turn your attention to Yshiggol. There is usually a safe spot for melee types to stand and attack Yshiggol on the near corner of his slime pool, but ranged dps will make the battle go a lot faster. Yshiggol has one AoE attack which does 3-4k damage on your tank and knocks back, but it's pretty easily avoided. The Ustilagors don't do too much damage to armored types, but will make things rough on your healers and ranged dps, so put a melee or tank on protection detail. Keep up the dps on Yshiggol until he gets to about 2/3 health, at which point, he'll become untargetable, and Stage 2 will begin. Stage 2--Miniboss At this point, Yshiggol will spawn an illusion of the Pirate King and a fresh set of mind flayer/ustilagor adds. The miniboss is easy to deal with, provided you have a player with a Knockback skill up. Just lure the illusion to the edge of the arena, and knock him over the side. Then deal with the adds normally. Once the miniboss is dead, Stage 3 begins. Stage 3 Same as Stage 1, only without all the death-defying tentacle-dodging to get to the safe area. Burn down Yshiggol until he gets to about 1/4 health, at which point, he'll become untargetable again and Stage 4 will begin. Stage 4--Second Miniboss The second miniboss will be an illusion of a random endboss from another Dungeon Delve (so far, I've seen the pit fiend from Helm's Hold and Hrimnir the Frost Giant Jarl) and a fresh set of mind flayers and ustilagors. Some illusions will be immune to knockback, meaning you'll have to burn them down the old-fashioned way, making this the most-difficult part of the whole fight,  apart from the initial run to the safe area. Hrimnir in particular will need to be lured to the safe area--tricky since his preferred attack allows him to snipe with boulders from halfway across the arena. The Pit Fiend, on the other hand, periodically despawns and reappears back at his original spawn point. There is a spider miniboss you may get, as well. Once this second miniboss is dead, Stage 5 begins. Stage 5--Victory Lap The remainder of the fight is pretty anticlimactic--deal with any remaining mind flayers, then burn down Yshiggol the rest of the way.
 * Graft-Harrow
 * Yalghoor the Rank
 * Yalghoor the Rank
 * Yshiggol, The Elder Brain
 * Yshiggol, The Elder Brain

Loot
{| class="wikitable" ! Epic Boss !!Guardian Fighter !!Great Weapon Fighter !!Devoted Cleric !!Trickster Rogue !!Control Wizard !!Hunter Ranger !!Misc. Loot !!Seals
 * Graft-Harrow || - || ||  ||  || - || ||  || 3-5
 * Yalghoor the Rank || - || - || - || - ||  || || - || 3-5
 * Yshiggol || - || - || - || - || || || - || 3-5
 * Yalghoor the Rank || - || - || - || - ||  || || - || 3-5
 * Yshiggol || - || - || - || - || || || - || 3-5
 * Yshiggol || - || - || - || - || || || - || 3-5