When i read the LN some time ago, i think i read about another mage whoms destructive power would outmatch Ains but, Ains' skill was better or something? Could you guys please enlighten me, and yes i have read on the wikia
That would be Ulbert, He has one of the World Disaster class and his spell.
Grand Catastrophe: It's an ultimate move which requires 60% of his mana. Its destructive power outstripped the might of even super-tier spells. This spell is capable of wiping out five elementals, which should have been at full health, were instantly annihilated.
This attack practicall is the ultimate nuke spell in all yygdrasil, he firther specialise in spells with high fower and attack power, however since his mana drain is so large, his is more suited for insta kill techinques than prolonged battle, which ainz is better at.