Strike of the Giants (Fire Giant) (UA)

You have absorbed primeval magic that gives you an echo of the might of giants. Choose one of the kinds of giants listed below. As a bonus action, you can call on the power of your giant magic to imbue your attacks with additional power. The next time you hit a target with a melee or thrown weapon attack within the next minute, the target takes an extra 1d8 fire damage.  You can use this bonus action a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest.