According to Ghostcrawler on the Cataclysm Beta forums, here are the class synergy thoughts for Cataclysm as of today:

Balance druids will be providing spell haste and spell damage increases.
Agility and Strength – Death Knight, Shaman, Warrior
Armor – Shaman, Paladin
10% AP – Marksmanship Hunter, Enhancement Shaman, Blood Death Knight, Paladin
Burst Haste – Shaman, Mage
3% Damage – Beast Mastery Hunter, Arcane Mage, Retribution Paladin
Health – Warlock (probably Destruction), Warrior, Priest
Mana Pool – Mage, Warlock (probably Affliction)
Mana Regen — Paladin, Shaman, Warlock (probably Affliction)
Replenishment — Shadow Priest, Frost Mage, Survival Hunter, Destruction Warlock, Retribution Paladin
5% Crit — Fury Warrior, Feral Druid, Subtlety Rogue, Elemental Shaman
20% Melee Attack Speed — Shaman, Frost Death Knight, Retribution Paladin, Survival Hunter
5% Spell Haste — Shaman, Balance Druid, Shadow Priest, Destro Warlock
6% Spell Power — Mage, Shaman
10% Spell Power — Elemental Shaman, Demonology Warlock, Fire Mage
5% Stats — Paladin, Druid

12% Armor Debuff — Warrior, Rogue, Druid, Hunter
10% Physical Damage Debuff — Warrior, Druid (probably bear), Protection Paladin, Warlock, Blood Death Knight
30% Bleed Damage Debuff — Arms Warrior, Feral Druid, Subtlety Rogue
30% Cast Speed Slow — Warlock, Rogue, Arcane Mage
5% Spell Crit Chance Taken — Fire Mage, Warlock (probably Demonology), Mage (possibly Frost)
25% Healing Taken — Arms Warrior, Fury Warrior, Hunter, Rogue, Frost Mage, Shadow Priest
10% Melee Attack Speed Debuff — Warrior, Death Knight, Feral Druid, Protection Paladin
4% Physical Vulnerability — Arms Warrior, Combat Rogue, Frost Death Knight
8% Spell Damage Taken — Warlock, Unholy Death Knight, Balance Druid, Assassination Rogue

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So I was driving across a few states today, heading home for the long Thanksgiving holiday, and I begun thinking about [Focus Magic], and how broken it was (and the fact that an arcane mage will in most cases receive both sides of the buff in benefit, as long as there’s >1 mage in a raid), and I was thinking of how it could apply to druids.  I think a neat ability would be some sort of boost / synergy based on the other druids in the raid.  A moonkin could draw on raw energies from a feral druid, and be granted extra damage, for example, as well as draw on the spiritual powers from a resto druid, which would grant additional haste.  Perhaps a moonkin could also draw from another moonkin, granting it something like critical strike.

Anyways, I’m not sure exactly what bonuses could be granted, these are just quick ideas, but I do like the general idea of balance druids being able to draw synergy from their fellow druid forms to gain some sort of benefit.  This is something that could perhaps be a base ability/low in the resto tree, and allow for all druids to be able to gain some sort of benefit from the other druids in their raid.  What do you think?

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