Talisman: Digital Edition

The Poltergeist is one of those "bad" followers that will hamper your progress. It reduces your movement to one space per turn, and can only be getting rid of by crossing the river using the bridge, a raft, or the ferry.

Getting rid of the Poltergeist will grant you the Poltergeist Exorcist reward at the end of a game. Do that 10 times and you will unlock this achievement.