@wizzid Try knockback units, like the Witch, Centaur, Dwarves, and cannon fodders, like Zombies and Goblins. Just keep going, wait for max population, and CHARGE! Took me 15 tries, but I did it in my other acc. Up yer damage with spell, Meteor and lightining to stop the lil' bugger. Focus on the castle.
All you guys that complain about revenge waves: YOU HAVE SPELLS GODDOMIT! If they overrun you, Phoenix razes the whole ground. Save some spells for the revenge waves: If they overrun your army (never happened to me), kill them with fire. Magic Cannons and spellcasters are the best units in the game: use them.