Mother Smolderweb

Skitterweb Tunnels
Continue beyond Voone through the Firebrand passages into the spider tunnels. Clear the approach before engaging Mother Smolderweb, and leave space behind the tank for the rest of the group to avoid Crystallize. Remove Mother's Milk before moving onward so its immobilizations do not follow the group into another pull.

Mother Smolderweb
Elite BeastMother Smolderweb tests frontal-cone positioning and poison removal because Crystallize disables players in front while Mother's Milk can immobilize nearby allies.
Abilities

Crystallize
Stuns enemies in a cone in front of the caster, rendering them unable to move or attack for 6 seconds.
Leave the frontal cone to the tank; Crystallize stuns players caught in front of Smolderweb.

Mother's Milk
Poisons nearby enemies. Until the poison is entirely removed from the bloodstream by a knowledgeable medical professional, it will periodically immobilize a poisoned individual and any nearby allies.
Remove Mother's Milk as a poison and avoid clustering around an affected player while it remains, since its immobilization also catches nearby allies.
Tank- Hold Smolderweb with Crystallize aimed into the cleared tunnel, away from the rest of the group. Set the position before the cone can stun you.
Healer- Stay outside the Crystallize cone so you can heal through the tank's stun. Remove Mother's Milk rather than letting its recurring immobilizations disrupt the next pull.
Damage- Work from Smolderweb's sides or rear. If Mother's Milk remains on you, separate from allies until it can be removed.