Got the amulets for 30,000 monsters killed and 60,000 monsters killed on the same day. Also went from level 30-something to level 65. Crap, I'm gonna fail out of college.
The revenge waves aren't really that big a deal. Especially since you have a few spells at your disposal that can destroy almost every unit on the battlefield. When the revenge wave hits, just pull back to give them all time to get on screen, and then use the phoenix.