This was good! Fun way to strategize with which units to bring! It took me a while to figure out that the wizard towards did splash damage to my units, so since I could only bring 5, it might have been good to display some information like their health since they would often overlap and I could not tell who had what health. This way, it would be easier to see all their health going down from splash damage and adjust my strategy.
One suggestion I have would be to lean into one way or another - either if the player can only watch, making some QoL changes to speed things up since I found myself getting annoyed at having to repeat the last level a few times to grind some of my characters to a high enough level to win.
Or option two: if the player should be involved, making some way for the player to interact / command/ or assist the 5 units somehow. Some ideas would be a fire / freeze spell, commanding which units should be up front so they dont clump for splash damage, etc.
Some minor bugs: sometimes the sprites would get stuck in their end state for an attack and slide across the ground. Sometimes a fireball would appear from my wizard or their wizards and just freeze on screen and disappear.
Otherwise, great job putting this game together- this was great!