Reaper is a spirit in the Chest of Rage.He is the guard of the Temple of Time.
The chest of rage is powerful, even to capture a guard of the temple of time. When thieves arrived from Demonis, they stole the Mirror of Fates and he was sent to chase after them. The chest was then used to capture him.
He will serve you only if you find the lost Clock of Time and return it to him - it is the symbol of the uard and resource of strength. He points to the location in Kordar.