NOTE 2 ALL: if you read the walk through and its misinformed, that is because it was made for the original version of the game. I believe they made changes to the game and fixed some bugs.
use all the range units u can accept the witch... and use the basic goblin. wait till your fully spawned and rush. keep the boss back with spells till u reach the base but dont use the spells to soon. when ur at the base use the def/att boosting spells so you can kill the castle fast and if it hits u, u will take 0 dmg.