have around 50k defending balis. in compact mode, they will outrange the incoming balis. and with a good atk hero defending, the losses will also be low on def side. well if u don have enough balis to kill incoming ones in a round or two, then use pony for def. the point is killing the damage dealing balis as soon as possible and ur city will be safe.

also a few k defending catapults dish out serious damage on slow moving balis for a couple of rounds i guess....