Challenge 2: if u cant kill the tower before the bomb, kill it and use shield. then lets your units go at castle and redo it. Use Rage and Berserk to kill tower before you go at the bomb. Challenge 3: use mighty guardians at ball, once they are at him, the sword will hit behind them, use lightning to kill the succubus (arrow rain and ice blast also might work).
advice for epic challenge 1: sky dragon to survive when 6 black imps will attack your castle once their tower is running low. use the stone throwers as the stones will bounce on to the castle. and use fast units as tiger warrior (if you got mana use shield 100% crit and attack + once you have a few units at castle). Challenge 4 , epic yeti. Sometimes he doesn´t hits untis that is just below him.
 "Epic Battle Fantasy 4"){kind=icon}
 "Epic War 4"){kind=icon}