***Let me just say right off the bat, at the time I'm making this build, Omenak is prone to crashing and if you want to armor farm here, be aware the game may just shut off at any point, best if you lower graphics settings to low before starting as that seemed to help reduce crashes.

Overall pretty simple build. 

First use an Aura Monk to place the auras as close as you can and then build the Lightning and Deadly Striker Tower (1 in each direction) Stacks on the ledge as far out as possible.  Then place a boost beam on it and upgrade that beam to max.  You then have to place temporary boost beams on the auras stacks until they touch the maxed boost beam.  Once they reach, sell the temporary boost beams, all the auras should reach the central stack/boost beam. 

Place the other two boost beams as shown and see minion build at note 2 (minions are here used as walls to keep mobs off the tower stacks and web ogres) one build of minions on each side, on each boost beam. 

Place traps and web walls as shown (this helps with overall mob management and keeps little guys off the south craystal.

One Seed Bomb plant shooting West (for fun really) to additionally cover the wyverns and genies that spawn out there.

First wave, if starting early, just upgrade with whatever, but if you're starting on later waves (23+), you'll want a Tower Boost monk to help upgrade or the initial surge will overwhelm the build.  Once fully upgraded, it can hold up with summoners rocking dual guardian pets.  Huntress/Monk x2 or you can also do Huntress/Monk/Huntress/Apprentice Guardians.

Due to sheer numbers on this map, recommend 2 summoners at the stacks.  Flash heals should be able to reach every element except the gas trap and web walls (which never need it anyway).  Likewise if you bring in a Tower Boost Monk on later waves, to speed things up he can stand near the stack and boost everything.