User blog comment:Fainz/Question/@comment-29707962-20160823060448/@comment-173.25.157.91-20160823234429

Pretty sure it was stated to be 5th tier. Either way, the tier of magic isn't the only factor in how powerful a spell is. Fluder's tier 3 fireball all but crippled the Martial Lord. A level 15's fireball would probably just bounce off of him.