Allies are people that offer to assist the investigators in their adventures. Allies are the most powerful investigator cards and can be found either at Ma's Boarding House (a location on the game board) or through encounters at some of the more dangerous and unstable locations in Arkham.
“Margie, pack your bags!”
Allies and terror
The most obvious effect of the terror level is that people pack up and leave town. For every point the terror level goes up, select one Ally card at random from the Ally deck and return it to the box. That Ally is no longer available for the rest of the game. Once all Allies have been returned to the box or claimed by investigators, this specific result has no effect for the remainder of the game.