This creature is a large grayish-black rat about 2 feet long.
Ethereal Rat CR 2
Speed 20 ft., climb 20 ft.
Melee bite +4 (1d4-2 plus ethereal poison)
Special Attacks ethereal jaunt
They attack by biting a foe and then jumping to the Ethereal Plane. If badly wounded in battle an ethereal rat uses its ethereal jaunt ability to escape to the Ethereal Plane.
A victim that reaches Strength 0 from an ethereal rat’s poisonous bite becomes ethereal (as if affected by the etherealness spell). The victim remains in this state until at least 1 point of Strength damage is healed.
Organization pack (6-11)
Ethereal rats, like normal rats, they can be found just about anywhere.
Ethereal Rat from the Tome of Horrors Complete, Copyright 2011, Necromancer Games, Inc., published and distributed by Frog God Games; Author Scott Greene.