A good strategie is to get a group of monsters that like to attack defensive towers and a group of monsters that enjoy looting yards. send the defensive tower attakers in first and once they have cleared the way back them up with looter monsters.bolt and brain are both looter monsters. tower attackers are octo-ooze, Ichi, crabatron and project-x.even better than tower attakers is a gorgo of any level.
Drull and two zafrretis are powerfull and will destroy a yard no trouble. drull is really fast and zafreetis are really slow so they have to be quite close together for good effects.