It may just be that Pikmin 4 just released, but I could totally see you selecting a couple of units to spawn, and then a separate button to “send” them all at once. Likely with a limit so you can’t just brute force your way through. As is, it feels difficult to coordinate an attack.
As for the interface, it was a bit hard to parse at first. A nice touch that I liked was that you could see the exact effect of a unit on your resources as you hovered over them. The confusing bit there was the spell to “burn” towers, since I thought it was a unit. Maybe having the word “spells” next to it would suffice? Or split it into a different bar?
On the aesthetics side, the visuals and sounds really work well together, and the font feels “old timey” but also pixelated to not stand out. Good job!