Kaio Ken

As a bonus action you can activate Kaio Ken, you must maintain concentration to keep it active and must succeed a (dc 10) concentration check at the start of each of your turns it remains active (the dc increases by 2 each of your turns it remains active) This feature can be used 2 times per short rest.

While active you have advantage on strength saving throws and deal 1d4 extra damage when you hit with an attack

At the start of each turn take 1d4 points of damage

(The extra damage done by attacks and done to you at the start of your turns increase to 1d6 at level 5, 1d8 at level 10, and 2d12 at level 15)