Malefic grasp and drain soul could easily be combined to reduce necessary keybinds.
But I can't see drain soul either in that ss, so I'm not sure what is happening.
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Doubt demon bolt will refund the full 300 DF if you don't have max when you use it
Also, with the damage reduction of FnB, the AOE chaos bolts may actually be balanced.
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As he was a prot warrior(against mobs, not some raidboss stacking millions of vengeance), the 3k would actually be really low. However the numbers could be placeholders.
As for 100% uptime of meta(if even possible)... stack mastery, mastery and more mastery, get 100% uptime on mastery buff, spam 1111111 like a good little arcane mage