Board Thread:Questions and Answers/@comment-176.20.223.62-20171129215549/@comment-5480911-20171130141848

That would be Ulbert, He has one of the World Disaster class and his spell. This attack practicall is the ultimate nuke spell in all yygdrasil, however since his mana drain is so large, his is more suited for insta kill techinques than prolonged battle, which ainz is better at.
 * 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.