Thanks for the tip Axhiil. The second mission was so much easier to figure out. Just put a dog, bird and ant, beat the armor scarab and switch the ant for the rat. At the final wave, just keep beating the snakes while shielding the rat
Iconian, all upgrades make it better, thats why they're called upgrades.
Like you, I maxed everything way before the sixth track, and I beat the sixth track in the first try.