Nice, polished game.
Bull toads are just OP, the enemy damage output is capped at one attack per column per turn, so 5 attacks per turn, and one bull toad tanks 5 attacks, so if you have 3 flower toads you’ve won. Actually 2 flower toads is enough if you refund the bull toads right before they die - which is a really tedious mechanic because you don’t show their health. Maybe it gets more difficult later on, I didn’t play past wave 2. The turns progress really slowly due to having to wait for each individual enemy animation.
Also, this isn’t a Deck Builder in any way.