A phase spider, sometimes called a wraith spider, is a large blue-green spider that can leave the Material Plane for the Ethereal Plane on a whim and return the same way.12 Four ambushed the party in the cavern before the Fardrimm Gate on the Vigil of Remembrance, 1714 PSF.2
Appearance
Phase spiders are blue-green, and large.2 One of the four at the gate was bigger than the rest, a huge one.2 Their webbing is very hard to see at first, even with darkvision and even for someone who has tracked giant spiders. Up close it gives off a faint, pale blue-green glow with a rippling light running across it, and has a strange, wispy translucence.2
Behavior
Like the giant spiders of the deep, phase spiders are ambush predators that lay webs and like the dark.2 They seem to turn invisible or teleport: they appear out of thin air beside their prey, bite, and vanish again.2
Their venom is pale teal and bitter.2 It can paralyze a victim for up to an hour, but only one who is already nearly unconscious.2 An ordinary person sprayed in the face with it would be paralyzed for an hour.2
History
Session 13
Near the gate the party found the tail and back left leg of a giant rat, and webbing running from the pillars, before four phase spiders appeared out of thin air around them.2 The biggest tore into Rhysaene until she hacked its head apart with her greatsword. Iva and Temerity killed the last two.2 Hazel knew them for what they were only afterwards.2 She harvested one dose of venom and was sprayed in the face trying for a second, and Luma collected goop from the biggest.2