You can take a Bonus Action to summon up a well of determination. Until the start of your next turn, you gain the following benefits. Once you use this feature, you can't use it again until you finish a Short or Long Rest. You can also restore your use of it by expending two Battle Dice (no action required).
Unbreakable
Whenever you take damage from an enemy, you can roll a Battle Die without expending it and reduce the damage taken by that roll.
Undaunted
Whenever you fail a D20 Test, you can roll a Battle Die without expending it and add it to the roll, potentially causing it to succeed.