Cool concept. I think the execution leaves something to be desired. Specifically, there is no excitement for the player.
You get to click once every few seconds, and eventually you win.
I think this is fundamentally a tuning issue, which, I get is tough in 48 hours.
For my two cents, I would suggest (if the enemy is that OP) being able to spawn LOTS of minions, and potentially having the enemy be able to move.
This would allow for things like cornering or flanking the enemy.
Also, I assume the crossbowmen go all the way to the enemy because he can't move, which kind of defeats the purpose of deciding between ranged and melee attacks.
Thanks!