Unholy Tower is another piece of crap dungeon that less than 1% of players trying it will ever even hope to succeed. Be sure to get Xenon AND the Princess? Yeah right. Attacking with 5 and 6 star units still means you spend 5 or 6 gems and STILL don't acquire them. Buy More Gems. Buy more gems. Spend $50 or more for the "pleasure" of buying more again. And guess what. You still lose.