I am currently working my way through the dungeons on Vet, and am writing a guide for them. This guide will be edited a multitude of times, so don't expect a finished guide for at least a week.
Brought to you by the guild Twin-Moons Covenant
Frostvault Guide
Add Priority: Skysplitter
Every trash pull, focus down the Skysplitters otherwise they'll cast deadly Ice Comets on the players. Make sure you block this ability if it does get cast on you.
First Boss
Icestalker
Icestalker is the first boss you come across so this troll isn't too difficult to take down. He does have one main mechanic to watch out for, which is when he punts some up into the air and stuns them on the ground. The boss must be interrupted otherwise he'll start mauling the downed player and kill that player very quickly.
Several adds spawn in, but they are of low threat and can easily be AOE'd down.
Second Boss
Warlord Tsogvin
Tsogvin is a more mechanically challenged, and some of them we have seen before. The first one is the boss will randomly choose a player and shield charge that player. This is very deadly to unsuspecting DPS or Healers. This is easily blocked and/or dodged though to survive. The second one we've seen before in Fungal Grotto II is a tether between two players, and the two players must simply put enough distance between each other to break the tether and stop the damage from occurring.
The arena will have goblin archers spawn in, that can be chained in by the tank. The archers do have some powerful abilities, including Rapid Fire (the bow ultimate), which cannot be neglected. They can be cleaved down when chained in fortunately.
The boss will periodically jump into the air (he leaves a fire visual effect on the ground from where he jumped from). He'll land at a random location in the arena with a small shield on top of his health. During this mechanic, every player will have an AOE ring around them and the boss will be channeling a fire ability that will hit every player in pulses. Do NOT stack on top of another player when this mechanic is occurring. DPS must break the shield in order to stop the mechanic from occurring (very similar mechanics to vMoL first boss).
Ice tornadoes will spawn at approximately 30% (health percentage still needs confirmation) on the edge of the arena and slowly circle the arena. These are very deadly so avoid them at all cost. During this phase, the boss will still do his jump, but this time he'll always land in the center of the arena and begin channeling a blizzard storm around him. This blizzard will grow larger rather quickly, pushing the players into the path of the ice tornadoes. Simply follow the ice tornadoes to keep ahead of them until the blizzard storm is over. In addition, the boss will cast one more ice tornado on a random player, so this extra tornado has it's own path (that of the player) to add to the chaos.
Vault Protector
This boss is rather difficult (and had a few glitches that wiped our group). The boss itself is very simple, and we've already seen its mechanics many times. The Centurion has the basic heavy attacks, spinning attack and artillery attack that we seen in Darkshade Caverns I and Volenfell.
The arena mechanics however are lethal. Most notably the laser beams that line the four walls of the arena. These lasers will kill you if you are caught in them. Fortunately the laser beams can be blocked by an obstruction as seen below. In the fight, the obstruction is the boss itself as it is protecting itself from the laser beam with a Dome Barrier. Simply put the barrier between you and the beam's source to survive.
Laser Beam:
As the fight continues, according to the boss's health percentages (? Needs confirmation) more lasers will activate during each time the Protector puts up its barrier. This will require more coordination and awareness to dodge each laser as it gets closer.
Several adds will be spawning which will make life increasingly more difficult. The Dwemer Spiders will snare anyone they hit, the Dwemer Spheres will outright kill the DPS if they get caught by a spinning heavy attack, and the smaller sphere things will stun everyone near them if one person touches their AOE.
Tank: Tank the Vault Protector in the center of the room so a laser doesn't cut off the group if it starts in an inconvenient location.
Rizzuk Bonechill and Avalanche
Rizzuk is the only boss that needs to be killed; once killed, his Frost Atronarch will be destroyed.
Rizzuk will occasionally channel an ability that will need to be bashed. If not bashed, this mechanic will start shooting every player in the arena in a rapid fire method, (same as Fang Lair HM mechanic).
Ice Meteor Shower is a mechanic where the boss will teleport to the middle of the arena now place a DoT on each player that will also slow you all down. Eventually each player will be frozen and an ice meteor will crash into each player. You must all have been sufficiently separated, otherwise the stacking impacts will kill any player that were stacked.
Now and then an ice ball will be created by Rizzuk and follow a random player. This player will have a target underneath them. The ice ball doesn't do much damage, and it is unknown on any affects if it is dragged into another mechanic or a boss.
Avalanche, the frost atronarch, is deadly and will be the primary focus of the tank. Avalanche will put down some AOE's around him that even the tank must dodge roll out of since it does significant damage very quickly.
The StoneKeeper
Rat Maze mechanics:
The rat maze is first introduced before the final boss fight. Each player will spawn in the map above, each at one of the four arrows seen on the map. You are a mechanical mouse with unique abilities. Each player needs to go to the center pillar that is electrified and spam the first ability on your bar to charge up your ultimate. Then follow the lit path that you spawned at until you get to another orb pillar thing, and use your ultimate. Four of these Orb Pillar Things must be deactivated, one for each player, which is why it is recommended for each player to go their own way for speed.
The rat maze will occur twice throughout the fight.
The Stonekeeper itself is invulnerable until both his arms are destroyed. Much like the Halls of Fabrication Assembly General, one arm has fire and one arm has a spinny blade on it. DPS will need to focus the spin blade first. A Centurion will spawn once an arm is destroyed, and it must be killed as soon as possible. It's heavy attacks will one shot all players through block except the tank, and the tank cannot take that much damage with the other mechanics.
Once both arms are destroyed, and the boss reaches a health percentage, both arm sockets will begin to spout and fire, and the boss will then slowly spin. Do not get caught by this fire! It will kill you practically instantly. This is difficult to do with the spheres that will stun the group if they are touched. The boss will repeat this mechanic until it's next health trigger percentage.
Both arms will regenerate, and then 4 mechanical mice will spawn on the arena. Each player must get to their own mouse quickly, and repeat the Rat Maze. Be warned, traps are now active within the maze. Your mouse will be deactivated if you lose all health, which you can press the second ability to bring yourself back. Any damage taken the Maze will carry to the boss fight when the mechanic is complete. That also means, if you're deactivated when the Maze mechanic is finished, you will be dead once you return to the boss fight.
The fight is more or less "rinse and repeat", since now you repeat the same with destroying the arms. The only difference during this second phase is that there are no spinning blade traps that will apply stacking bleeds if you are hit by hit. Dodge roll through it if you cannot avoid it another way.
After the second Rat Maze phase, the boss will begin spouting out steam at a random player. This steam will push you off the arena, resulting in an instant death.
Tank: Taunt the Stonekeeper, do not worry about taunting the Arms as they will focus you down if the Stonekeeper is taunted anyway. The Stonekeeper itself will shoot you with a firebeam now and then which does not hurt but does stack a DoT on you that the healer must keep you alive through. Dodge the spin blade arm if it attacks you, and tank the fire arm.
