Unwavering Self

Sokan Form: 7th and 15th level If you fail a Strength, Dexterity, or Constitution saving throw, you can reroll the die. You must use the new roll. Once you've used this feature, you must complete a long rest before you can use it again. At 15th level you can use this feature twice between long rests.

Granted by Sokan Form at 15th level.