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[Reynhart]

If you have issues with Black Mage hotbar management, then I'm going to assume your bars are trainwrecks because you already don't know what you're doing to begin with.

Then stop assuming and start thinking, maybe it will help you realize that Blizzard IV and Fire IV are as mutually exclusive as Inner Beast/Fell Cleave and Steel Cyclone/Decimate.
Therefore, there is literally no good reason for them to require two slots in your hotbars.