Good Old Fashioned Grinding.
As it is right now, the gods had succeeded in hampering him a little. Something had to change or he wouldn't be able to make much progress in destroying the catapults.
The spell he had used was enhanced by amplified and delayed casting. The two spell techniques are tasking on their own but to use them simultaneously is too draining. He can handle it better if he were not creating and maintaining barriers. He is extraordinary for a vitality core stage refiner but he has reached his limits. He has reached the limit of what he can do against an army of that size.
But the ranged war machines have to be destroyed or all the attempts of the attackers to push into the dungeon with the army will be nullified and their current expedition will go to waste.
The only good news is that he has the energy to become a mana entity right now. The killing spree he had just gone on paid with a bounty of energy. Now he has a choice, become a mana entity or create another gate.