The doors to Yar'Lir's lair seal shut when Yar'Lir hits 95% health.
Hits for around 4400; enrages; AE rampages (mitigated to ~900-1000 per hit).
Sees invisibility; does not see Shroud of Stealth.
Yar'Lir is permanently rooted.
Other forms include Yar`Lir the Hurricane`s Eye, Yar`Lir the Mistress of Winds, and Yar`Lir the Matriarch. Whichever form she is killed in will spawn the chest with loot.
In hurricane form, an unstable storm spawn in the perimeter of the room. They cast "Force Quake", a strong hp/mana DoT -- avoid them.
In matriarch form, spawns many of a blizzard seeker. These cannot be avoided.
After she's killed, a chest spawns with additional loot.