One of my favorite games so far! Sequel would be great!
Lil' Tip:
When using Warrior what I do is put alot of them to one side like the bottom bit and little amount to the top (this probably will work better if you have all the bombs) and rush the ones at the bottom to reduce their hp and use bombs at the top to kill the ones which do not get rushed )
Wizard : Just spam the area and full wipe them, I gave my wizards full attack, works fine
Spear-men : Umm.. Yeah same as magician spam the area and spam their ability..
AND don't forget to use hotkeys for the bombs, much easier.