Interesting entry for the theme! I liked the story, overall mood, various and funny enemy designs (I wonder what the old ninja do to those pink tigers, so they come to him for revenge? x)). After a couple of tries, I managed to get to the finish, though only by ignoring all the enemies xD Though, I've managed to try all the combinations of runes in action.
I agree with some of the commentaries that the level design is a bit too brutal. Also, some enemies have no animation for preparing the attack - hence why I ended up skipping them all. If you want the player to kill them, I think it would be nice to at least give more clarity for enemy attacks, and give a reason not to skip them (for example, score). Another suggestion is to change health combination to heal, instead of temporary buff (I think it would encourage the player to fight, and the health combination is least useful at the moment anyway).
Overall, thank you for this fun little game! I will be looking for post-jam version, and wish you even better projects in the future!