D&D Basic Monster: Phase Spider

The Phase Spider is an advanced form of the "normal" giant spider. In addition to normal spider abilities, such as poison, spider climb and web walk, it has the ability to skip between the material and ethereal plane, which gives them an excellent opportunity to ambush and surprise its foes, and evading retaliation.

The Phase Spider first appeared in the Greyhawk supplement for the original D&D, and has been featured in the main monster book ever since, though often sharing a stat block with various spiders in general. The mechanical aspect of the Phase Spiders ethereal jump has varied over time, often making them nearly impossible to attack unless the characters were fast or clever enough.

In terms of look, there was initially no real discernible difference between a Phase Spider and a normal Giant Spider.The Phase Spider got a make-over in the Monstrous Manual for second edition, where the Phase Spider was described with a "raised thorax, and human like head", a play on the similar pronunciation of phase and face.

By third edition the human like head was gone, and it was from that edition it gained the pale while and grayish blue colour palette that has stuck with it since.