Nice game, would like it if the balls didn't pop from the same spot when squished. Little bit better collision detection for squishies would rock.
Good job!
Correcting this comment ..
"If you just have warriors and rogues, you won’t be able to get to the boss if he’s in the back row."
You can get to the back row by killing everyone in the front row.
Miyamoto kill dark mobs with bash towers or any upgraded tower. Immune is just immune to slows, creeps just need to beat em down until they split enough that they die.