Build buff beams, auras, and all of pin 1 mortars. Then have a hero during combat phase QUICKLY drop mana for mortars on pin 2.
If the core warps to pin 3 during first wave the build will fail unless you either get lucky on warps, or you have a dps pet sit at pin 3. (Gamble or just have a dps or a dps pet sit there.)
After the first combat wave the build easily holds with no issues and summon your other 2 splits on last wave.
TB monk can sit on pin 4 inside the building to boost pins 2/3 and splits with guardian pets can sit at pin 1 (optional)