Path of the Slayer

In the first age, in the first battle, when the shadows first lengthened, one stood. He chose the path of perpetual torment. In his ravenous hatred he found no peace, and with boiling blood, he scoured the Umbral Plains seeking vengeance against the dark lords who had wronged him. And those that tasted the bite of his blade named him . . . The Doom Slayer. 

UNTIL IT IS DONE

At 14th level, your fury drives you to finish your injured foes, leaving no fiendish survivors in the wake of your rampage. While raging, when one of your attacks reduces a creature at 20 or fewer hit points, if you have already used your Action and Bonus Action, you can make one additional attack action against it. If the target is a fiend, attack rolls made as a part of this action gain advantage.Also at 14th level, you gain access to the Legendary Longsword, Crucible. If you have mentored some one in the way of the Hell-Razer, they may use this blade at 10th level instead of 14th, and thank you for carrying on your legacy.