Magic Item: Gambler's Shoes
These fine leather shoes have embroidered hexes on the outside of each shoe. They magically change size to fit whoever is attuned to them.
As a bonus action, the wearer of these shoes can click their heels together granting them incredible speed or crippling slowness. For the next minute the creature’s movement becomes 1d12 times 5 feet (5-60 feet).
The wearer of these shoes can call on the gods of luck to grant them special abilities. Once per day, as a reaction, before you roll a d20 you can choose to roll two instead. You choose which to use now, the other roll is reserved and can be applied before another later d20 roll.
A twist of fate. If your reserved roll has not been used, the DM can choose to apply it for you on any d20 roll.