Strike of the Fire Giants (UA)

You have absorbed primeval magic that gives you an echo of the might of Fire Giants. As a bonus action, you can call on the power of your Fire 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.