On mobile so tower orientations are not correct (and ignore the arrow idk how to delete lol).  Two golems face right, back five seed bomb face right, and then the side seed bombs facing the crystal.  Stats might be able to be lower, but mine were roughly what is on the build. 
 

All the seed bombs can go up before starting first wave, golems go in before starting second wave.

Golems draw aggro, thus we don't need walls. Make sure the golems are far enough from the crystal; if they are too close orcs hit the crystal when attacking the golems.

Side seed bombs sometimes get attacked, but they should be placed slightly in the range of the golems and so any troops attacking the side seed bomb towers die from the golem.  The back seed bombs every once in a while get hit but should be fine.

I stand on the center back seed bomb towers during waves, sometimes do one mana run then go back on top.  If you do get off make sure you don't draw aggro and bring enemies to your back five seed bombs, nothing protects them from behind.

Upgrade towers throughout, I do golems first.

Crystal might get hit now and then but who cares, we here for the loot!  Can always whirlwind with Hermit in a pinch to knock enemies back.

This build can be done with four players.