Spawn some zombies when you're first starting out. Don't waste money on weapons or pots, get that gold mine. On the big towers, put 1/4 Turret Tower with max speed and arrows, no bounce, and the 3/4 put shulker necros (Excludes leach tower.) For small towers, at the start of the path put lots of bounce zeus, as they can take out massive swarms, and near the end rally an army of babies. When you're done with that, work with your team to amass an army of WITCHES, giants, magmas, and blazes. It really helps :D