Discovering how to best utilize each hero's unique abilities is the key to success in the turn-based battle of Days of Doom. Attack with Pyro early in the fight, as he ignites enemies for continuous damage.
Then, combine Hydromancer and Thrasher in a double knockout blow. Hydromancer can set the stage with a ranged water attack, and then Thrasher can deliver a shocking surprise to the soaked enemies. The odds against you may seem insurmountable, but if you strategically use your heroes' abilities, upgrade them, and add new abilities along the way, you might just make it.