A primal path for barbarians.
BLOOD AND SAND
Starting at 3rd level, whenever you make a melee attack that drops a creature to 0 HP, you gain temporary hit points equal to your Constitution modifier; while you are raging, the temporary hit points you gain are equal to your Constitution modifier plus your rage damage bonus.
If you have any temporary hit points at the start of your turn, you can expend them to gain a bonus to the damage roll of your next melee attack.
EXCELLENCE OF EXECUTION
At 6th level, whenever you make an attack roll with Advantage and both results would hit, the target of the attack must succeed a Strength saving throw (DC = 8+the damage roll) or be knocked prone or moved 5 feet in the direction of your choice.
At 10th level, when you roll damage for a critical hit on a melee attack, add another die of damage for every die that rolls a maximum result.
When you reach 14th level, you can use your reaction to re-roll a failed saving throw with bonus equal to your Proficiency bonus. After using this ability, you must complete a short or long rest before you can use it again.