1st phase - Traps + auras
2nd build - Minions: Top + Bottom 4 Archers+Mage+Spider, Middle 3 Archers+Mage+Spider
3rd build - buffs, some walls
4th build - remaining EV towers
Proton beam icons mark the hidden switches. There's enough time in the initial build phase to push all of them and get extra mana for building all auras. If you can't do it then build the healing auras in a later phase.
Things get tricky last wave, you need to DPS the evil heroes. I suggest using huntress/ranger with blaster + cat as main char and monk + chicken with controller/emulator. Always kill the squires first.
#2: Stand between the minions and wall
#4: Place your monk here.
#1: Boss fight area
If you lack the DPS to kill the squires at #2 before they mate up you can try using chicken instead of cat but that'll make the fight with cupid even more annoying.