Using My Pillar
After every big wave of rock attack, a wide space would be created, like a void in the middle of the ground. I instantly summoned a group of warriors there to fill this gap and add more chaos to the enemy backline.
At first, this didn't do anything remarkable or worthy of note. But when the enemy took time to kill my forces, I managed to plant more warriors in other places.
Gradually this became the greatest source of trouble for the enemy. After all, any army would be tightly arranged at the frontline, with slightly loose formation at the backline.
So hitting this unprepared backline and in such a hard way to control, adding to it the help of the falling rocks at the forces down below, things started to look better for my side.
Gradually the forces scattered in the middle of the enemy managed to clear lots of them, and eventually they started to merge together and form bigger sized forces.