I like the tower defense theming! I had an idea for a TD for the jam as well... but nothing like this! Overall I liked how the towers get absolutely wild with the more interesting effects.
I have two points of critique:
* I did not understand how towers did damage, and how to influence that damage with other towers. I feel the game did not help me understand this.
* I think the enemies also were affected by the elements in the towers? I couldn't tell. It seemed fire should be countered with water but I didn't have much success trying that strategy. Seemed the most effective strategy was stun + do raw damage.
Strong game, though! I liked how the game got progressively more wild, as good tower defenses should :)