Glory Kill

You shred a stunned creature apart with your bear hands, using the pure bloodlust of battle to rip and tear the creature apart. In doing so, you extremely violently tear the creature to pieces, invariably covering yourself in the creature's blood and guts. On a hit, you roll 2d8 and add your strength modifier and proficiency bonus, if you are proficient in unarmed strikes. If the result is higher than the creature's remaining hit points, you instantly kill them and they do not make death saving throws. On a miss, you may attempt to Grapple the creature.

The dice roll goes up to 3d8 at 5th level, 5d8 at 10th level, 8d8 at 15th level, and 10d8 at 20th level.