Originally Posted by
Grog
An interesting theory a LS member brought up that has worked sometimes but not others, is that when the ancient magic buff is up, any spell of that element you cast will boost the spells damage. So if you cast Flare, then Burn II, Fire, Fire II, cycle, it will actually enhance the damage of the Flare. It's seemed to work on some mobs but not others, so your testing would be great as well.
Also, if you're going to use Profundity or Blood Rite, make sure you use them in the last 10 seconds or so of the buff, and not when casting the initial spell to get the damage boost.