Lord Walden is one of two of the Gilnean eastern lords convinced by Lord Godfrey to go with his plan. Later he was resurrected by the Forsaken along with Lord Godfrey and Baron Ashbury and have fled into the Shadowfang Keep along with his companions shortly after the failed assassination attempt on Sylvanas Windrunner. He is the fourth boss of the instance.
Heroic: Move to avoid Ice Shard target spots. Try to avoid the Poisonous Mixture target. The Toxic Coagulant (green icon) debuff can be removed by jumping or moving (the tank can simply jump in place each time the debuff is applied). The Toxic Catalyst (orange icon) debuff gives a 100% damage bonus, so save damage CDs for this part (when Walden is at 35% health). AE heals are important for several abilities.
Abilities
Regular
Heroic
Conjure Mystery Toxin: Causes one of two spells to occur -
Toxic Coagulant - Deals 11100 to 12900 damage every 2 seconds and applies a Toxic Coagulant, which, at 5 stacks will cause the target to become thick as ooze. Movement will render the toxin unable to fully coagulate.
Toxic Catalyst - Used only once, at about 35% HP. Deals 9250 to 10750 damage every 2 seconds, but increases critical strike chance by 100%. Note: Movement, or lack of, does not affect this debuff's damage.
Ice Shards - Ice shards erupt in all directions, dealing Frost damage and creating ice patches that deal additional frost damage.
Conjure Poisonous Mixture - Hurls a poisonous mixture at the target and surrounding enemies, dealing 12000 initial damage and seeping into their skin for 5700 to 6300 damage every 2 seconds. Movement speed is slowed by 40%.
Conjure Frost Mixture - Summons a frosty mixture that deals Frost damage and freezes the ground, dealing damage to enemy units within 15 yards of the target.
Walden will frequently begin the fight by casting Conjure Mystery Toxin. Depending on the effect, he will glow either red or green, and this effect is commonly compared to traffic lights. Green means move, red means stop.
Lord Walden will glow green, casting Toxic Coagulant - if you see this, you should begin moving. It is very similar to the debuffs from Keristrasza or Hodir; move or die.
At about 35%, Lord Walden will glow red, casting Toxic Catalyst. The damage is not avoidable, but the debuff will increase DPS. Pop offensive and defensive cooldowns here.
Tip: While many people out there claim that Toxic Catalyst only inflicts damage if the player moves, this simply isn't true - you'll continue to take damage whether you move or not. However, to take full advantage of the positive effect of the debuff, you should stand still and DPS hard.
When he uses Ice Shards, the shards arc up into the air and crash down on pre-targeted white spots in the floor. To avoid being hit by these, keep moving away from the white dots on the floor.
He will also cast Conjure Poisonous Mixture and Conjure Frost Mixture periodically. The Poisonous Mixture can be cleansed, and the ranged should just be spread out for the Frost Mixture.