Stuck on Battlefield 11... can't manaboost fast enough to get the dragon, let alone the angel, before I get killed by a dragon AND a fire-demon within about 30 seconds!
I hate that invisi-goblin (Trail Cave 5). Finally beat it by a) reading most of the comments on here and b) hitting "retreat" a lot until my army was maxed (except the fire titan, who never actually got to show up!) and c) sending the whole thing (Hero, dragon riders, succubus, Phantom armors, Yeti and Black Knights) to play "knock knock" on the castle while the Lightning bolt spell had the invisi-goblin stunned and my army was protected by Athena. The invisi-goblin had just become a threat again about 5 seconds before the enemy castle fell...
I've still got some heroes to play as, but I've got all the badges now! ^_^