Change a spell from buff to debuff

Good morning, I’ve been looking around everywhere and can’t find where to change a spell from a buff to a debuff. The spell in question is ignite mana which is used in Molten Core and it should be a debuff but it shows up as a buff you can just right click off. I’ve been looking through the database, spell dbc, and even the core and I can’t find anything.


(Note I’m NOT trying to submit a bug report. I’m trying to learn how this works so I can fix it and possibly change other spells in the future.)