Clockwork amulet

A clockwork amulet was a magical amulet that removed all variability due to chance from a single action.

Description
The copper amulet contained small internal gears that constantly emitted a very faint sound of clicking and whirring.

Powers
The clockwork amulet drew its magic from the Outer Plane of Mechanus. Once per day, its wearer could use the amulet and invoke exact predictability from a single attack. The amulet ensured that the outcome of the attack was perfectly average, given the wearer's abilities. The amulet then regained its magic at the next dawn.