Back Blast

When cast The user is able to absorb 1/2 the damage they take for 1D4 rounds and store the damage to add to their attacks in the form of shock waves.
A loud boom is heard as a shock wave is released from the casters fist as they make an attack. 

Upon casting the user gets all bludgeoning damage reduced by half and rounded down to the nearest even number and the damage reduced added to stored damage for 1D4 rounds.

When making a successful attack while the spell is active the user is able to add any amount of the stored damage to the attack.