This works on any starting wave. Can full build on earliest wave, works without issue starting wave 32 as long as you pre-upgrade buff beam before starting. I dont have issues mostly upgrading the main stack then heading over to upgrade the west when the aura HP starts getting a bit low.

Credits:

Rumple - Protecting west crystal with just a gas trap + stack

Antibeck - This is essentially his Forest Ogre Crush build with the above changes.

All web walls and physical beams are 2 DU. Avoid standing next to the physical beams under any circumstances. Ogres and Obunga Ogres wont attack the walls if you're not near them and basically be infinitely stuck without doing any damage. That's the cheese to the build.

Hint 3 - Place your TB here and aim at hint 4. You will run out and need to re-enable mid wave but you're pretty safe

Hint 5 - Place a hero here with a DPS pet that can repair the auras. Either a DPS monk that you can just TB a little bit or a jester. I use a wheeler jester with a little wizard just to wheel to make things easier/faster. You need the pet due to spiders spawning behind. If an obunga ogre comes up and gets stuck on the crystal just walk back or under the bridge and itll run away - happens in rare circumstances. Summoner with pets can also work. Depending on how close to the crystal to place the auras you can also sit under the bridge where the chest is and repair through the wall - you wont be aggrod from here but I like to have a view of what's going on.

I usually use a double huntress summoner on the tower stack but you can also use a monk + huntress and it works about the same. Can't see a difference in wave times as the owls can reach far already and the holy cannons don't need a range boost.