I place 1 summ with hunt/monk guard at each stack and then my tb and secondary tb with ev guard on at pylon. Tb will reach both stacks from there. You can also use your builder warden with djin on instead but I don't have one for builder sadly :(
I would recommend a 9k aura monk and range hermit for this.
Make sure the elec aura hits the bb after pylon is fully upgraded, the wyverns can get nasty at that side.