T1-succubus,wizard,witch,hobbit,goblin(flaming chariot),inferno. a variant from DEVILaffect's suggested units, who would put in a black dragon instead of my inferno. as the dragon is later pretty useless against the colossus, i prefer inferno, who kills enemies behind the boss.T2-its not really hard, dragon(omega seal) as a tank and regen are important, all you need is MUCH patients ;) the rest should be ranged or titans, as minions are too easily killed.T3-use some good attackers, and use spells to lure the bosses one by one away from the rest to fight against your army.T4-many think that the beast just runs past your army, but the truth is that it lets your army run past it...so use the iron fortress(omega seal)+regen, as its too slow to run past the beast. dont let the fortress die(regen).T5-pretty easy, use some tanks(dragon, iron fortress) and if you want, some goblins too, in order to stop the boss from moving. omega seal/slash ring to units with low slash resist.
questions? pm!