Pretty basic build that has been working for me. I am by no means a master builder, I made this up and it worked out, I don't have a good summoner, but some strong minion units could make this a decent Survival strat

Most of my builders have low level gear (Apprentice has all Mythical, initiate has 2 Transcendent Armour and a Fish In a Bowl, Hermit is full Mythical and a fish in a bowl, and EV is 3 mythical and a godly but has a transcendent Genie, giving her some extra tower stats) I put as much as I could into Monk Auras, They cover a pretty chunky area around all crystals. If my EV and Apprentice had better stats, this build could be AFKable, based on aura size, pretty much everything dies, mini ogres are a slight issue with my current tower stats but earlier waves I find them to be fine to deal with.

Both the far right crystals have issues with Copter ogres, I find myself running back and forth as Jester or Huntress to add some extra DPS to deal with these, but with some better gear and stats on my EV or Apprentice for towers and the defences should be able to deal with them, especially on later waves.

Wave 1 - I place all Auras, all buff beams for Auras, the reflection beams around the middle crystal, the proton beams on the stairs heading up to the top right crystal, and one Lightning Tower on the buff beam at the top right crystal

Wave 2 - I add all Lightning towers and the proton beams in the cross by the middle crystal, If I have enough mana I place the Forest Golems, they're useful as a wall, and can keep the ogres busy in the middle whilst the towers and auras whittle them down

Wave 3 - Pretty much everything else. The Physcial beams and anything I didn't place on the other 2 waves,

I recently got myself a good mana gathering Jester, I am using her in Combat phase to gather mana and upgrading as much as I can. Prioritisng Buff beams, then Lightning Towers, then the 2 physcial beams. After that all auras and Golems

Note that the proton beams heading up to the top right crystal may need a few upgrades if lower tower stats, the later the waves, the healthier the enemies are going up there, may take some extra damage. 

Hope this was helpful. I have never done a build before, but I thought this worked out quite well for me and it may work even better with much better tower stats. adding minions is the next step, I need to build up a powerful summoner.