
Originally Posted by
Suiram
Sorry if I sound like a broken record about this lately, but MDB of the mob doesn't matter for comparing the % increase from adding MAB, just how much MAB you already have. MAB+5 is a roughly 3% increase at +65MAB for the reasons Spekkio showed, but that's going to be true whether the thing you're fighting has MDB+0 or +100.
Also, if you want to get super technical, you also have to make a similar comparison for "bonus damage added to magic burst" equipment and bonuses. So for instance, if someone has Lv3/5 AM2 and AF2 hands and wants to know the bonus from adding static, it's 1.16/1.11 ≈ 4.5% increase. The difference here is that there aren't enough "MB bonus" options around to let the MAB overtake the MB bonus options in ear and hands slots in any practical situation, except possibly af2 gloves vs. morrigan hands when also using static and the hands participating in the morrigan set bonus--depending on other gear. Also, there's a new staff from La Vaule which I doubt has some massive bonus worth even using over HQ staves, but if it did that would also change the considerations above.