as an action,  you make an extremely loud low pitched tone that has a high enough energy to push every creature within a 15 foot diameter 5 feet back and deal 1d4 force damage, you can optionally cast this as a reaction, a would-be attacker must make a con save with a dc equal to 8 + your spell casting modifier, if they succeed, their attack lands and they arent pushed back, if they fail, the attack fails and they take 1d8 force damage.