Works for 2-3k stats until about wave 25, then you might need 3k stats on apprentice damage.

This is the bare minimum Pure Strategy TD. You don't need a lot of stats to pull it off. Depending on your stats, add another lightning strike turret, barricades or strength drain on top of the slow auras.

1. Put down your auras as close as possible to each other, ideally on the stairs. There you can use a 4 DU buff beam to buff both of them to save DU's.
Additionally, if you have 4000+ damage on the apprentice, you can just leave it at 2 towers there.

2.The first round consists of putting down all the auras, the buff beams and only one lightning strike turret on every lane.
After that, put down the rest and upgrade the buff beams first, then auras, then turrets. Except for 3. These turrets can get jumped by spiders, so you might get them to level 1 or 2 (depending on your damage) to increase that damage.
Alternatively, if they get a lot of damage, put down strenght drain auras where you might need them. Those tend to get a lot of damage, so look out for them.