Givin the latest update dropped, I'd ask for a means to defeat bosses with charm (for challenge runs), a primary weapon that does little/no dmg and instead slows the target, and if you eventually add a significant amount more waves some kind of familiar/partner system.
Also, for balancing reasons - I believe you should add a 5 second timer for the duration of the charmed enemies (paused during animations). At the moment chain charming is very easy and permanent.
-Love your work!