Brutal Combatant

The brute force of your attacks leaves enemy combatants bruised and broken. You gain the following benefits:

• Increase your Strength or Constitution score by 1, to a maximum of 20.
• When you are making an attack with advantage using strength, if the lower of the two dice would also hit, the target must make a Strength saving throw or be knocked prone. 
• When you are making an attack with disadvantage using strength, if the higher of the two dice would have hit, the target takes bludgeoning damage equal to your Strength modifier. 

Savagery: when you score a critical hit or reduce a creature to 0 hit points with a melee attack on your turn, you may use your action to make a display of savagery. Each non-friendly creature within 60 feet that can see you must make a wisdom saving throw or become frightened of you for one minute. A frightened creature may use an action to make a wisdom check against your DC to steel its resolve and end the effect on itself. This ability can only be used once per short rest.

The DC for all effects of this feat equals 8 + proficiency + your strength modifier.