To everybody complaining how to beat the bosses, just attack the one with the highest damage. Once you get in his radius he can't attack you anymore. The key is to reproduce all the time and send one or two to make new expansions while the others are dying and reproducing at the same time, i.e. distracting the bosses.
One thing I noticed is that when you press your mouse and go off screen you can pass some obstacles that are usually in your way; knowing this playing is so easier. Great game 5/5 !
To make simpleharmonic's comment easier to read: For maps without bog or holy towers, use 2 goblins, a healer, a shield golem, four goblins, a shield golem, a healer, and finally 2 goblins. You want the healer first, because the shield golem's have alot of health and if the healer dies, they can survive much longer. On maps with bog or holy towers, you want: A goblin, a healer, a cleanse warlock, a shield golem, four goblins, a healer, a cleanse warlock, a shield golem, and finally a goblin. The reason you want healers ahead of warlocks is because they heal for less than the bog or holy towers do, so you want him to die before the cleanse warlock. Please don't - me because of repost. I was just making it easier to read.