I got to the black heart after the trampoline. Then, I tried to go back to the part with the sea-saw type platforms and now I seem stuck. I cannot move but the background moves.
Just beat impossible stage one in 11:01 with lv5. Warlock. I like it that even if you lose you gain exp, many other games are very frustrating in that if you lose a long battle you gain nothing.
I beat impossible first stage with warlock. Lost first time after 33 minutes then won in 16:21. Those upgrades really made a difference. When enemy warlock hero uses abilities with a few powerful units just retreat your hero and let your tower kill their hero. Then, when your hero is ready charge with every thing you got blowing all cool downs before enemy hero can respawn.
33 minutes and 20 seconds I lasted on impossible stage one until I finally gave up. Opponent's tower had 5-6 cannon balls and was rapid firing. I could have last much longer with upgrade three times drakes defending my quadruple cannonball tower. Well, I got 9 skill points so I'm guessing you can beat the first stage eventually by just losing over and over but gaining exp. Not sure if the last stage on impossible is beatable, would need every skill upgrade.
Finally lost, took 20:21 seconds. That slave stacking really changes the strategy. Also, the hero commands are a little bit awkward. Meaning if your two heroes are pitted against each other the A.I. can hit blood lust plus battle slam before you can and win before you can do anything.
Seems fighting fire with fire is the only way out. I was finally able to break the siege by doing the same. There is a bug the A.I. uses, that if you build a bunch of slaves while the enemy has a bunch of melee at your tower, that the slaves cannot march forward and will stack in one huge stack. They will then all attack at once annihilating assassins and even heroes easily.
Pretty sure I lost time on normal. I got the ai backed up against its tower. Then, it built 20 or so slaves. The slaves were able to attack 10 at a time. Normally only 2 can. I can't seem to recover.