I myself haven't done any calculations or theorycrafting on this subject, but I recall a comment regarding the usefulness of Molten Armor coupled with MoE (and a certain lvl of crit) vs. Mage armor in the PvE and boss encounter environment. Could anyone please provide some information regarding at what point, or if ever, rather, Molten Armor comes ahead of mage armor in mana regen?
I don't think mages use molten armor as a substitute for mage armor in terms of mana regen, but the exercise would be fairly simple.
Personally I regen 28 mp/tick using mage armor.
If I'm chain-casting fireballs, assuming some cast lag lag, I'm using around 230-ish mana per tick.
3% extra crit giving me 30% back is around 1% mana returned, so 2.3 mana per tick.
So basically if you had so little spirit that you'd only get 2.3 mp/tick from mage armor, it'd be worth using mage armor for the regen.
However, the whole question itself is flawed. You use mage armor for the DPS increase, not mana regen. When you get a shadow priest and you use your pots/gems properly, you can sacrifice the extra mp from mage armor for extra DPS.
I was under the impression that the only time you should ever use Mage Armor in raids is when you know you're gonna be fighting over a long period of time like on Nightbane. Usually I only use Molten Armor. After all, you can go a fairly long time rotating mana gems and mana pots if you've got a 10/48/3 build, and I'm lucky enough to have a great shadow priest on many of my raids who provides a fuck ton of damage and mana/health regen.
If you have a good Shadow Priest in your group, you probably don't ever need Mage Armor. I used Molten Armor our last Gruul kill with a Shadow Priest and did not go OOM.
That said, it's all about pacing. Your damage pool will probably go down if you use Molten Armor on any significantly long fight... but, that's really an issue in regard to how quickly your raid group kills stuff.
I typically use Mage Armor for most bosses, though...and Molten Armor for trash. But, Shadow Priests pretty much make mana a non-issue, so then the choice is easy.
I use Molten pretty exclusively, although I do have an in-group shadow priest for anything but 5/10-mans. Even when I don't, I'd rather use mana pots aggressively than shift to Mage Armor and that is sufficient for all but the rarest situations.
While my guild isn't as far as a lot of yours, I prefer to use Mage Armor exclusively. I have 190 Spirit and according to the tooltip, I get 45 Mana / 5 Seconds with Mage Armor on (the only buffs active are AI and Mage Armor). With Mark of the Wild and Blessing of Kings, that will increase of course.
Fights tend to be long enough that I really notice the difference between not having Mage Armor up and using it. Even with Gems, Pots and an Evocation macro (to swap in a high SPI weapon), I still find myself running short on mana over long fights, DPS intensive fights (like the Prince or Curator).
Finally I'm Deep Frost so I don't get the benefit of Master of Elements. I've taken all the efficiency talents and still can run low by the end of some fights.
Ok here is the issue I am having I have been trying to research on the brutalis fight. IE is he immune to his own fire debuff, if i get burn would molten shield tick per tick if I took 2/2 instead of the say dragons breath and blast wave that are not used in that fight, hence the question about being immune. Any help on this subject would be greatly appreciated links, feedback, etc...