I usually don't like the generic games, but this one's really got maybe, it's the slappmedo-like art, fluid controls and spells, which make it less repetitive like other similar games.
TIP: You can switch spells after they're on cooldown...but while they're not in your five slots, their cooldown freezes, but this is still good for using an ultimate every save/you still get to use more spells. You can also put multiple long cooldowns in your slots, and use "downtimes" to get it back, if you're okay with losing a bit of gold, you can do that between waves (I was wondering what the point of skipping was, as unlike kingdom rush, multiple waves can't go on at once).