Alden Lascar's Modified Chronolometer

This small locket has intricate runes engraved on the face and small gears within. There is a small button on top used to activate the ability described below. 

Time Bandit. At the start of your turn, roll a d6 (no action required). On a 2–4, you slow down time, gaining an additional action on your turn and doubling your speed until the end of the turn. On a 5–6, you go forward in time to warn yourself of what is to come. The next time you fail a saving throw, attack roll, or ability check, you can reroll the check and take either result. On a roll of 1, you become frozen in time momentarily, losing your turn. 

The device has two charges. Once both charges are expended, it cannot be used again for 24 hours and only after being recharged (level 3 or higher lightning spell)

Notes: creature with an Intelligence of 14 or better. Must be charged with some type of lightning or electricity