This is really cool! Having to chant, dodge rocks, collect things and pierce the heart really made for a challenge! I really liked the chanting and once I got into a groove, it felt really good. I liked how there was generally a pattern to the chanting (with a few mix-ins for challenge).
I think it might have been cool if you're encourage to chant in-time with the drum for a bonus, or penalty if you don't, but I think I found myself in my own natural cadence anyway.