Tales of the Valiant Players Guide (pg. 127)
Through rigid mental exercise, you have fortified yourself against mind-altering effects. You gain these benefits:
• Once per short rest, when you fail an INT, WIS, or CHA save, you can choose to reroll the save and take the new result.
• When you start your turn charmed, frightened, paralyzed, or stunned, you gain 1 Luck.