I just keep getting killed by the ghosts on Lvl 22. The arrow storms a few levels prior always kill 1+ of my mages. I mean, I beat it, but only with 2 stars.
I just passed this level on normal difficulty without any (!) abilities at all for 3 stars. Try to change your tactics, and find a way to protect your casters while they eliminating the incoming ghosts.
Okay, I'm having a lot of fun with this game, but I have 2 problems.
1) I don't always recieve the reward for quests
2) Sometimes, after beating a campaign level, the games gets stuck. The game still registers me (I can surrender) but it doesn't progress.
Oddly enough, I found stage 13 to be much more difficult than stage 15. Stage 15, all you need to do is rush, and you win in less than a minute, even at the hardest settings.
 "Royal Warfare"){kind=icon}
 "Magic and Empire"){kind=icon}
 "Cursed Treasure: Don't Touch My Gems!"){kind=icon}
 "Swarm Defender"){kind=icon}
 "Siege Knight"){kind=icon}
 "Symbiosis"){kind=icon}
 "Incursion"){kind=icon}
 "The battle of Undermountain RTS"){kind=icon}
I just passed this level on normal difficulty without any (!) abilities at all for 3 stars. Try to change your tactics, and find a way to protect your casters while they eliminating the incoming ghosts.