Bell of the Dead
The Bell Of The Dead is located at the southern shore in Dungeon Doom. Ringing it will summon Chyloth the Ferryman, the NPC who takes players across the River Mortis to the Gauntlet side of Doom. If you do not give him a Golden Skull (the payment required to cross the river), he will spawn a Skeletal Dragon to attack you for wasting his time. This dragon must be defeated before he can be summoned again.