Ponpoko-Pon!

Whether it's because you play especially vigorously or are simply off-key, the music of your belly drum can physically wound your foes. You deal 1d4 per 2 levels (rounded up) sonic damage to all creatures in a 30-foot cone, with a basic Fortitude save equal to your spell DC or class DC, whichever is higher. Such vigorous drumming does leave your belly a bit sore, though, preventing you from using this ability again for 1d4 rounds.

At 15th level and every 2 levels thereafter, the damage increases by 1d4.