In Permafrost (regular zone): PH is a "giant wooly spider" at approximate location 950, 20, -80. It flurries, summons, and fights to the death (doesn't flee at low health).
In Permafrost (Level 90 revamp): Known to spawn right outside the door to Lady Vox's lair.
Respawn time is around 1 hour real time.
Spawns on progression servers when Lost Dungeons of Norrath unlocks.