The graphic here has the crystal much more East then it is in the game. there is a lot of space to build on the West side of the crystal, which is where this is setup.
Speed build interation 25...
Party: Tower Boost Monk and 3 Summoners with guardian pets (Huntress/Monk each)
Activate Tower Boost when you are about 200-300 kills into the wave and it should hold up until the wave is just about over, you can kind of AFK it after that. I just have TBMonk auto-fire northward.
Hint 4: Just using up the extra MU here with a mass of archers