Ras Frostwhisperer

Laboratory
Clear space around Ras before the laboratory fight so Fear and Chill Nova cannot carry players into another pack. Kormok is a separate optional summon in this room; leave the brazier unused unless the group has come prepared for its shield and summoned attackers.
Ras Frostwhisperer
Ras FrostwhisperElite UndeadRas combines group Frost damage with Freeze, Fear and Chill Nova, testing whether the group can keep healing and interrupting after losing movement or control.
Abilities

Frostbolt Volley
Prioritize interrupting Frostbolt Volley to prevent group damage and its movement slow from overlapping the control effects.

Freeze
Stuns an enemy and inflicts Frost damage every 3 sec. for 15 seconds.
Dispel Freeze from a player who must heal or interrupt. It stuns its target while continuing to deal Frost damage.

Chill Nova
Blasts nearby enemies for Frost damage, knocking them back and reducing their movement speed for up to 10 seconds.
Tank against a cleared wall and keep ranged players away from Ras's close-range nova, which knocks back and slows its victims.

Fear
Strikes fear in an enemy, causing it to flee in terror for up to 8 seconds. Only 1 target can be feared at a time.
Clear the routes around the fight before pulling Ras. Remove Fear if possible so its target does not run into another laboratory pack.
Tank- Use a cleared wall position to limit Chill Nova's knockback. Keep Ras within the group's interrupt reach when movement resumes after a nova or Fear.
Healer- Remove Freeze or Fear from the player whose lost action is threatening the group. Stay away from the close-range nova so a knockback does not interrupt recovery from Frostbolt Volley.
Damage- Arrange interrupts for Frostbolt Volley and keep another player ready when the assigned interrupter is Frozen or Feared. Ranged players should avoid the close-range Chill Nova.