I recently bought Spell Casting Mastery 3 after everyone said that was our best AA hands down, and that it provided a 10% savings on mana on EVERY spell, but to tell you the truth I have not seen this reduction in the least. I still use the same amount of mana to kill the mobs I've been killing before I got it, so, what goes?
A guildie told me it was random, with the % ranging between one figure and another, and with my Spec spells this might be the case, but not with the others. Did I miss something?

I also went with SCM3, which I got recently. Through out the acquisition of the SCM line, I saw a reduction of the mana used to Root/Rot Gnarled Treants in PoN. Although the reduciont chances at at 30% with SCM3, I see a lot of mana reduction on the spells cast.rI use atleast 1 Root(193 dd) and 2 DOTs atleast 4 times in a kill, now I seldom go below 65% mana per kill, with KEI and PoTC. I also use 2 DOTs and snare that are manaless.
I believe that SCM3 is worth the AA xp, unlike the Mental Clarity, which in my opinion is not worth it after the first level.

Aegweil 61 Druid.

If you want to test it.

Mem a high mana cost spell like PoG. Nuke yourself oom then med until you can barely cast it. You cannot cast a spell until you have sufficient mana to cast it without a specialisation check. After casting you will still have some mana left in your bar, enough to cast a smaller mana cost spell like a root. Thats your specialisation savings.

Although you now cannot go back and unlearn SCMIII, if you parsed this 1000 times you would find that you consistently have more mana left over with SCMIII compared than without.

The best part about SCM3 imo is noticably less fizzles! :)

I got SCM3 about a month ago, and definitely noticed a difference. At the time I was octa-quadding toilers in ME, and I couldn't quite kill all 8 before OOM before SCM3, but could easily kill all 8 after getting SCM3.

Of course, I already had SCM2 (duh), so the difference from that to SCM3 is only 5% per spell. If you are not hunting in ways that quickly empty your mana bar, you might not notice it, but you are getting the benefit.

And it's a constant 10% for each spell cast, there's no variation. Unlike MP focus items, which are variable.

Tat

the best thing about SCM3 is not that your mana pool gets bigger, but the mana you expend gets closer to your mana regen level. i found that i could do alot more with SCM3 (not so much with soloing, but in groups, and raids, but still very helpful soloing). I can still heal better(when it's just cheal the tank, med, cheal...) then clerics without SCM3... just because i don't run out of mana as fast.

DS