Monster Analysis: Phase Spiders

  • First Appearance: 16 Enter Vasselheim
  • Armor Class 13
  • Speed 30 ft, 30 ft climbing
  • Darkvision 60 ft, Passive 10
  • Average, Max HP: 32, 55
  • Damage taken ranged from 30 to 45 among five phase spiders

Unlike other giant spiders, phase spiders, in Matt’s words, are “loosely themed in the ethereal.” As a bonus action, phase spiders can shift from the Material Plane to the Ethereal Plane, and vice versa. By doing so, they can travel much like ghosts, invisibly and through structures present on the Material Plane. By doing so, they appear to teleport, disappearing shortly after attacking.

The poison phase spiders inject into their prey, while fairly potent, is intended to preserve their meal rather than kill. If the victim is reduced to 0 HP, they are immediately stabilized, but are considered poisoned and paralyzed for the next hour, even if they regain health. Victims are often blinked to the Ethereal Plane where the spiders can feed in safety.

This colony of phase spiders seems to have infiltrated the stronghold of the Platinum Sanctuary, mostly undetected due to the lack of need for the chambers’ actual use. While they seem to have mostly existed to provide a story reason for the party to have an actual challenge sealing the horn (yeah, WE’RE allowed to metagame, it’s what we do), the spiders also demonstrated that, as big and mean as they are, the horn is most definitely in the safe, platinum hands of something even bigger and meaner.