For farming some XP during the grind towards mythical gear. Gear was obtained through beating through the game on normal difficulty.

First Wave: You can place 12 harps down this wave. Run around the map and place 1 harpoon for each wyvern path, 2 harpoon for each door. One door will only have enough for 1 turret this starting round, I suggest the east as it only has to deal with goblins and archers. 

Second Wave: (Also during first wave combat) Place all buff beams and physical beams, making sure DU is correct to make sure you have enough for each gate and enough to cap out DU for additional XP.  After all walls are up, place a bouncer blockade in the corner then finish running around and placing the rest of the turrets (3 for each door) and placing 2 turrets next the east and south crystal to prevent any monsters from taking a different path and attacking the crystals

Third Wave and up: Make sure all buff beams get upgraded first and walls get repaired. During waves if walls get close to death then upgrade them! If trying to get max xp, you get a 1.3x mulitplier for no damage taken and 1.3x multiplier for no core damage taken, and a boost for having DU maxed out. I typically hide behind the bouncer blockade to prevent any warriors from running up while afk. GL!