The only difference between the Ranks of this spell is the base mana cost to cast it, and the base damage done by the Strike. When it first came out, it seemed to me that each succeeding Strike did more damage than the previous one; ie, if I cast Mana Recursion Rk. II upon myself and it proc'd 3x off of a nuke, the first Strike would be 875dd, second Strike would be 910dd, and the third Strike would be 945dd. However, since the nerf, I've noticed that ALL Strikes (again, for the Rk. II spell) are 875dd. With maxxed crit AAs, each Strike crits for exactly the same amount of damage (2100), so it seems they've changed the formula.
The Strikes themselves are Chromatic-based, no modifier. I've seen them be fully-resisted, and partially-resisted.
A single nuke can produce up to 3 Mana Recursion Strikes, each of which can crit. I have seen it proc 3x on more than a few occasions, though it is by no means common. With all nuke AAs maxxed, you can land a single nuke for around 11k damage. This depends, of course, on the nuke itself (Polychromatic Assault Rk. II) critting, Mana Recursion proc'ing 3x off of that nuke, and each of the Mana Recursion Strikes critting; all for full damage.
Before the nerf, this spell lasted 2 minutes (more, depending on Buff extension AAs/Foci; mine lasts 3:24). Now, it lasts for 2 minutes (base) OR 20 procs...whichever comes first. This doesn't really affect Enchanters that much; even with a good Detrimental Spell Haste Focus, nuking constantly (ie, casting Polychromatic Assault Rk. II as fast as the spell gem refreshed), I reached the 20 proc limit just as the spell was about to expire.
This limit WILL adversely affect those with quick-casting nukes (Wizards especially, but also Magicians), causing Mana Recursion to drop much more quickly than the imposed time limit. Considering the recast delay on the spell, and the fact that we do not have a group version (unlike the Shaman's "Panther" line), this once again cripples what could have been an extremely useful grouping/raiding tool.
SOE stated that they implemented this nerf because Wizards were putting out some rather frightful numbers with this spell, causing Necromancers to complain about Wizards encroaching on their "soloing supremacy".
Obviously, SOE never stopped to think that, if a Wizard was prancing around "soloing" with this spell up, it was because he had an Enchanter nearby (either a friend, or as a boxed buff-bot) to constantly refresh it. By placing a limit on the number of procs this spell produces, they did NOT interfere with the Wizard engaging in this practice AT ALL; his buff-bot is standing by, ready to recast it whenever it's needed. What it DID do, is render US useless as anything BUT a "24-hour standby Mana Recursion buff-bot"; we simply cannot maintain this spell on any more than 2-3 people, thanks to the crippling limitations of spell duration, recast delay, and now the proc limit.
I personally don't know of ANY Guild who has 1 (active main) Enchanter per 2 nukers; too many of us have either switched to a Class that wasn't crippled (Clerics, generally) or quit EQ entirely. They've made some substantive strides recently in reversing the obsolescence of our Class, but it seems they're still so frightened of us that any useful spell given us must immediately be castrated for fear we'll over-run Norrath and render all other Classes useless. Honestly, can you imagine them doing this to the Shaman's "Panther" line, just because someone complained that a Ranger that had this buff could (hypothetically) approach the DPS of a Rogue that didn't?
Please join me in sending in daily /feedback regarding the Mana Recursion nerf. The spell was fine as-is, due to the limited duration and the recast delay; it's simply unusable now (as anything but a self-buff) with the addition of limited procs. Otherwise, they should just make this spell self-only, reduce the mana cost by 1/2 (or increase the duration by a factor of 10x), and let us awaken to the realization that, once again, they've provided us with a spell that looks good on paper...but sucks in practice. It'd fit right in with the other 90% of our spells (and AAs) that are completely useless.
We shouldn't be penalized because they gave Wizards insta-cast nukes that made the Necromancers cry (when do they not?) about Wizards being able to "solo better than a Necro". Nor should we suffer yet another blow to our already-inexistent grouping/raiding viability. Long ago, we sacrificed the ability to solo (effectively) in return for spells/buffs/abilities that made us indispensible to groups and raids. SOE has made sure that groups and raids no longer need us, but we're still saddled with the limitations of their "Class envisionment" of Enchanters being dependent on others to gain xp or even just stay alive. Remember, Clerics were also "envisioned" as a purely support-oriented Class; but SOE's given them the tools (Vow of Valor, Ward of Reprisal, Yaulp VIII) to solo more effectively than any Melee or Hybrid Class ever could.
Our true role is to improve the abilities of those around us to the degree that we make a significant contribution to a group (or raid), albeit indirectly. It seems SOE needs to be reminded of the "significant" aspect.