Well, at the moment it doesn't seem to work particularly well? Level-ups seemed to generally be non-permanent and seeing as the hero doesn't have an hp display and deals 10+ damage at lvl1, it really doesn't make much of a difference what monsters you place. So gameplay-wise, the game honestly seems sort of uninteresting in its current state.
The visuals are very nice. The art is stylized nicely and works in a way that makes it easy to forget that none of the assets actually have animation besides moving a png. It's coherent, thematic, a bit cute, and all in all this game's strong point.
The concept is very fun and handles the theme of the game jam in an interesting way.
This game has me hoping that development will continue. What's here now is a promising demo that warrants interest. I do think it's quite nice.