I'm DMing a new campaign and the players have to collect fragments of a magical tablet that have been spread across the world.

This tablet was incredibly powerful, so much so that even the fragments on their own hold great mystical power.

Each fragment they gain will have a powerful effect, a few are passive, but most are on use with a tenday cooldown.

I really would like to include a particular effect on one of these fragments, but I'm sure it has the potential to be abused or exploited. So I'm coming to Reddit to ask what you might do as a player to exploit this magic effect, and how you might consider fixing it.

​

Chronomancy
Use: 1 action

Cooldown: 10 days

Effect: When you activate this fragment of the keystone, the flow of time bends to your will. The world around you resets, and everything reverts back to the exact moment you woke up that morning. However, you retain all your memories and knowledge of the previous timeline.

Once activated, the Chronomancy ability goes on cooldown for 10 days, during which time you cannot use it again.

​