Obviously this is nearly pure speculation at this point, especially since talents are subject to change, especially in beta but also patches, but here is what I'm brainstorming with regards to group makeups. Incoming wall 'o text. I'm going to try to focus on the new synergies introduced in WotLK, or at least ones that are greatly affected by changes in WotLK.

Talent Specializations and the groups they buff:

Death Knight (Blood):

I'm not going to consider myself an expert here having only played the class through the tutorial, but it's pretty obvious that they belong in a melee group, either the tank group as a tank, or dps group when dpsing.

-Abomination's Strength - Spell - World of Warcraftis a 10% STR buff that with a 50% chance to proc on Blood Strike - Spell - World of Warcraft (the blood DK's bread and butter attack) or 100% chance on Obliterate - Spell - World of Warcraft, the uptime on this skill will be high--and even controllable. STR obviously benefits Warriors, Feral Druids and other Death Knights more than Rogues and Enh Shaman (who now only get 1 AP per STR) and to an extent Hunter pets as well so that would play into the calculations of the group makeup.

-Blood Aura - Spell - World of Warcraft The DKs heals, heal other members of the group for the same amount that the DK is healed. This would seem overpowered except for the fact that it requires Blood Presence - Spell - World of Warcraft meaning it is probably impossible for a main tank to use and improbable even for an off tank. The passive healing a DPS Blood DK would do on a tank (especially on an encounter where there is extensive raid damage) can't be overlooked though. This would also be beneficial on encounters where the Blood DK would be in a melee DPS group and taking steady damage.

Death Knight (Frost):
Seems to be a tree mostly focused on Tanking and Crowd Control.

-Frost Aura - Spell - World of Warcraft a deep Frost talent that grants 6% health for other members of the group. Clearly this would benefit tanks most. Worth noting that it requires Frost Presence - Spell - World of Warcraft the new DK tanking aura. Meaning that this talent is pretty specific to a DK Frost Tank as no DPS DK would use this stance in a raiding situation.

-Frozen Rune Weapon - Spell - World of Warcraft increases frost damage by 10%. Benefits Frost Mages, DKs (mainly the Frost spec'd variety) and to a very minimal or non-existent extent, the Elemental Shaman. This would also benefit non-Frost Mages using Frostfire Bolt - Spell - World of Warcraft (although I am currently unsure of the extent of the use of Frostfire Bolt in raids). I think it's safe to speculate that if you're going to be bringing a Frost Mage for PvE, they will be balanced around this buff and it will be required. Also worth noting that this talent is only Tier 3 in the Frost tree and can probably be somewhat comfortably taken by any DK spec. Whether the 10% bonus is worth it for a non-Frost DK is unknown to me.

-Icy Touch - Spell - World of Warcraft is a trainable skill for the DK. Every DK has it starting at level 55. Assuming the mob is not immune, there are other effects available to other classes that are more effective in every way. The improved version of Thunder Clap for Warriors is 20% melee, and Curse of Tongues for Warlocks is 50% casting speed. Still a single Frost rune use for a DK makes this skill easy to put up on a single target whenever needed so it may have some situational uses (aside from being part of a Frost DKs casting rotation).

Death Knight (Unholy):
In my opinion, this seems to be the most lackluster DK tree currently. Either that or the most unfocused. However it does bring some raid buffs.

-Unholy Aura - Spell - World of Warcraft stacks with other movement increasing buffs. This will be very encounter-specific in its usefulness. Requiring Unholy Presence - Spell - World of Warcraft means that it most likely will have little use for a tanking DK.

-Anti-Magic Zone - Spell - World of Warcraft is a situational but seemingly powerful ability. This mechanic has already been introduced in TBC in Magister's Terrace and also in Sunwell Plateau for the Kil'Jaeden encounter.

-Ebon Plaguebringer - Spell - World of Warcraft is probably the most beneficial debuff that any single class can bring to a caster-heavy raid, as 9% increased magical damage is huge. If I'm interpreting it correctly, as long as there is a disease on the target this will have 100% up-time as long ad the Unholy DK reapplies a disease to the target. Unknown to me (but probably not) if the attribute reduction works on bosses.

Druid (Moonkin):

-Insect Swarm - Spell - World of Warcraft has somewhat minor effects, however, as tanks get more avoidance through gear, the effect is more beneficial.

-Improved Moonkin Form - Spell - World of Warcraft is a casters new best friend. Assuming 100% uptime (obviously impossible) the bonus would be a net 26% up time X 20% haste for a net of about 5% sustained haste to the group. Depending on the Moonkins actual crit rate this will probably be more like 4% net effect. This is twice the effect of the current (and soon to be nerfed to 1/4 of it's effectiveness) flavor-of-the-week profession bonus, Haste Drums.

-Earth and Moon - Spell - World of Warcraft gives 100% uptime (assuming the Moonkin is always casting) on a 6% bonus to Nature and Arcane damage. Huge raid synergy here with Elemental/Enhancement Shaman and Arcane Mages and to a lesser extent some Hunter Pets.

-Improved Faerie Fire - Spell - World of Warcraft this new version includes caster +hit as well. Effectively 3% hit for every class in the raid when it is applied.

Druid (Feral):

-Leader of the Pack - Spell - World of Warcraft and Improved Leader of the Pack - Spell - World of Warcraft still exist, and the latter now includes ranged attacks, meaning in WoTLK the feral druid benefits the hunter group even more than it does currently in TBC.

-Infected Wounds - Spell - World of Warcraft reduces the attack and movements speed of the target by 50% when fully stacked. It is unknown to me whether this will effect bosses, if it does, this is going to be a huge debuff for main tanking. Even if it does not effect them, this is still an amazing talent for off tanking.

-Mangle (Bear) - Spell - World of Warcraft and Mangle (Cat) - Spell - World of Warcraft will be more beneficial in WotLK raids as opposed to in the past. The new Warrior ability Bloodbath - Spell - World of Warcraft and the newly changed Rend - Spell - World of Warcraft might be finding their ways into a Warrior's regular rotation and the synergy here is good. Worth noting that the Warrior talent Trauma - Spell - World of Warcraft will have synergy with Lacerate - Spell - World of Warcraft as well.

Druid (Resto):

-Tree of Life - Spell - World of Warcraft and Improved Tree of Life - Spell - World of Warcraft no longer require that the Druid be in the tank group, but the raid-wide synergy, especially for encounters with significant AoE damage, will be insanely useful. 40% of a level 80 Druid's spirit (assuming something like 800-1000 spirit) is 320-400 or more healing bonus for the entire raid.

-Replenish - Spell - World of Warcraft seems somewhat lackluster but maybe situationally useful. 15% chance per tick of Rejuv on a tank means that (assuming 100% rejuv uptime) means an average of 1 proc per 6.66 ticks or 10 rage every 20 seconds, or .5 rage per second. The usefulness of this talent clearly revolves around the amount of Rejuv spells the Druid has up at any time.

Hunter (Beast Mastery):

-Ferocious Inspiration - Spell - World of Warcraft is a nice little buff. I'm assuming, and I might be wrong, that this now is applied to the entire raid group, which means the BM hunter is really more affected by the group they are placed in, rather than the buffs they are giving their group. If the buff remains 3% to party only the effectiveness and placement of the Hunter is changed slightly, favoring a more "stacked" damage party rather than being able to put them outside of their current group configuration (with casters/feral druids/other bm hunters).

-Beast Mastery [NYI] - Spell - World of Warcraft is not yet implemented so it is unknown whether the new pets will have useful raid-or-group-buffing abilities.

Hunter (Marksmanship):

-Improved Hunter's Mark - Spell - World of Warcraft is a Tier 2 talent that can be taken by any spec, and can be used while the hunter is in any group.

-Trueshot Aura - Spell - World of Warcraft does not scale, and I believe it still only applies to the party. Still as lackluster as it is at 70.

-Chimera Shot - Spell - World of Warcraft seems to have some potential for some very situational raid uses (and also seems pretty mana hungry if used often). It is unknown to me whether the entire Marksmanship spec will have enough DPS compared to the other trees to bother bringing for this talent and/or TS aura alone.

Hunter (Survival):

-Expose Weakness - Spell - World of Warcraft is a great talent now and will continue to be in WotLK.

-Point of No Escape - Spell - World of Warcraft will be very situational if taken at all for PvE. If no traps are used on an encounter it would be completely useless. 6% bonus crits to trapped targets from everyone in the raid is a significant bonus, however.

-Hunting Party - Spell - World of Warcraft will be an amazing group buff. Assuming it procs an average of once every 10s or so, that's 2% mana every 10s (or 1 energy/runic power per second and .4 rage per second). Assuming 10k mana (very very low estimate for level 80) that is 200 mana per 10 or 100 mp/5 to everyone in the party. A great buff.

Mage (Arcane):

-Being a primary damage-dealing class, Arcane Mages bring little in the way of group or raid buffs (other than the standard Intellect buff, Food/Water and Polymorph utility). There is Magic Attunement - Spell - World of Warcraft if your raid favors buffing Dampen or Amplify Magic on the raid, however it is only 2 points for this 3rd tier talent and it can probably be fit into any raiding Mage spec (perhaps at the cost of some damage talents, however).

Mage (Fire):

-Again, Mages are damage dealers and fire brings little raid-wide buffs. Improved Scorch - Spell - World of Warcraft will be a staple in any Fire build and this marginally buffs Enhancement Shaman as well as the Fire Mage.

Mage (Frost):

-Winter's Chill - Spell - World of Warcraft will not only buff the Frost Mages DPS, but also the threat of a tanking Death Knight (and his/her damage as well).

-Winter's Grasp - Spell - World of Warcraft a seemingly weak buff, it may turn out to have some big synergy. Assuming that boss level mobs can be "considered Frozen", the Frost Mages and Death Knights will both receive multiple bonuses. Mages have Deep Freeze - Spell - World of Warcraft as their new 51 point talent and also Shatter - Spell - World of Warcraft for a damage buff against "Frozen" targets. The DK on the other hand has Howling Blast - Spell - World of Warcraft as a deep Frost talent and also Deathchill - Spell - World of Warcraft for burst and lets not forget the synergy with Frozen Rune Weapon - Spell - World of Warcraft and the Frost Mage as well.

Paladin (Holy):

-As far as I can tell the Holy Paladin brings very little or no group synergy, on the other hand they are greatly affected by group synergy themselves. Moonkin crit and haste and Shadow Priest mana and health return will be a factor in what group the Paladin is in. There is always the old, trusty, Concentration (and Improved) aura that after talents will put most other classes over 100% spell pushback immunity (assuming they have taken their own spell pushback talents).

-It is possible that Sacred Cleansing - Spell - World of Warcraft may end up having some PvE use depending on the encounter and debuffs applied, etc. Really it looks a lot like a PvP talent.

Paladin (Protection):

-Divine Guardian - Spell - World of Warcraft is theoretically in range (at the 4th Tier) of being taken by other specs but I think we'll find that it will end up as a mostly "Prot Pally thing". The possibilities of uses for this talent are huge as a 30% damage reduction for the entire raid for 12 seconds.

-Improved Devotion Aura - Spell - World of Warcraft adding an extra 50% more armor on Devo aura and 3% more healing taken is undeniably useful.

-Judgements of the Just - Spell - World of Warcraft will reduce the need to have a Warrior keeping the Thunderclap debuff up (and therefore making a raid less reliant on Warriors as a whole).

Paladin (Retribution):

-Heart of the Crusader - Spell - World of Warcraft brings 3% crit to the raid.

-Judgements of the Wise - Spell - World of Warcraft seems like a neat effect but is not targetable so the passive mana return, while theoretically good, will probably not be used to evaluate raid formation. I.E You wont be hearing people say "Let's get a ret pally in here for Judgment of the Wise!".

-Swift Retribution - Spell - World of Warcraft on the other hand is 3% passive haste to a party. Likewise Sanctified Retribution - Spell - World of Warcraft will give 2% damage to the raid. The combination of these two buffs will make a Ret Paladin highly valued. Also note that Sanctity Aura is gone and the talents now affect Retribution Aura - Spell - World of Warcraft instead.

-Divine Storm - Spell - World of Warcraft is very similar to Judgment of the Wise in that the heal is theoretically good (perhaps working to heal the lowest HP target like Chain Heal?) but the high mana cost and inability to target the heal will put it in the same boat, with regards to raid spot evaluation, as Judgment of the Wise.

Priest (Discipline):

-Previously this tree was "Utility" and then "PvP" oriented. However, in WotLK it may be a staple of any raid due to one talent Grace - Spell - World of Warcraft. 6% increased healing and 6% reduced damage on a tank is, as far as I know, the best mitigation buff that exists in the game.

-Don't forget the old Pain Suppression - Spell - World of Warcraft, Power Infusion - Spell - World of Warcraft (now with reduced cooldowns through Aspiration - Spell - World of Warcraft) and the slightly-directly-nerfed-but-indirectly-buffed (due to mechanics changes with other classes and specs spirit is a very desirable stat for Priests, Druids and Mages) Improved Divine Spirit - Spell - World of Warcraft, the Disc priest is getting a nice set of useful tools to apply to a raid.

Priest (Holy):

-New LOLLightwell - Spell - World of Warcraft is improved, but it still only benefits those who are mentally capable enough to click it so it will probably still be horrible based on the average intelligence level of the WoW population. Your mileage will vary.

-Inspiration - Spell - World of Warcraft should still be a bread and butter talent of any healing priest build. Note that it's easily taken by Disc priests as well (who are by default better suited for single target healing due to the lack of Circle of Healing).

-Holy priests also get a new "Oh shit" button with Guardian Spirit - Spell - World of Warcraft. Increases the healing taken by the target by 40% for 10 seconds and saves the target from dying once. Situational but theoretically very, very powerful and unique.

Priest (Shadow):

-Newly nerfed Vampiric Touch - Spell - World of Warcraft will keep raid leaders from bringing one for every mana using group (although the increased damage from the spec as a whole should slightly offset the loss).

-However, Misery - Spell - World of Warcraft and Shadow Weaving - Spell - World of Warcraft are unmatched and irreplaceable. This will guarantee at least one Shadow Priest a raid spot. Not to mention Vampiric Embrace - Spell - World of Warcraft is still a very good passive healing tool.

Rogue (All Specs):

-As with Mages, Rogues bring little in the way of group or raid buffs. There is Expose Armor - Spell - World of Warcraft which is useful if a raid has no Warrior tank (as it overwrites Sunder Armor, the primary Warrior threat generating ability), which should be very rare in WotLK, but perhaps less rare than a raid in TBC having no Warrior tank. Improved EA is superior to Sunder Armor - Spell - World of Warcraft so it may be used in place of Sunder assuming no Warrior Tank.

-Also the Subtlety tree has Hemorrhage - Spell - World of Warcraft which is a minor but effective physical damage buff. Currently in TBC, the raid-wide bonus from Hemo is inferior to the difference in DPS from a single Combat spec'd rogue. I am currently unaware whether this will change for WotLK.

Shaman (Elemental):

-Paralysis - Spell - World of Warcraft looks to be an effective way to reduce incoming damage. I'm assuming raid bosses will be immune to the effect as 75% reduced attack/casting speed is insanely good. Definitely a great bonus versus those mobs which are not immune.

-Totem of Wrath - Spell - World of Warcraft, as with other totems, is now a raid-wide buff, and is now very good. Wrath of Air Totem - Spell - World of Warcraft is also raid-wide but can be dropped by any spec'd shaman.

-The new talent Elemental Oath - Spell - World of Warcraft can stack up to 6% spell cost reduction and 6% more spell critical strike damage for the party. A very good talent that will be desirable for any caster group.

-The situational usage of Thunderstorm - Spell - World of Warcraft will probably be extremely useful on some encounters and only beneficial to the Shaman on others. Encounter design will 100% effect the usefulness of this ability.

Shaman (Enhancement):

-Unleashed Rage - Spell - World of Warcraft is a huge buff and now is raid-wide.

-Improved Stormstrike - Spell - World of Warcraft is new in WotLK and should increase the damage for Enhance/Elemental Shaman as well as Druids and potentially some Hunter pets as well.

-Improved Windfury Totem - Spell - World of Warcraft and Enhancing Totems - Spell - World of Warcraft are minor but significant buffs to their respective totem auras. All of these buffs combined will surely make Enh shaman a necessity in a raid situation, as their buffs are irreplaceable.

Shaman (Restoration):

-Restorative Totems - Spell - World of Warcraft, Mana Tide Totem - Spell - World of Warcraft, and Totemic Mastery - Spell - World of Warcraft are all now raid-enhancing buffs. Mana Tide still only affects the Shaman's party, so this would affect their grouping greatly.

-Spirit Link - Spell - World of Warcraft is a new situational talent that seems to be designed for fights with multiple tanks in close proximity. It is unique, and theoretically powerful.

-Obvious to anyone who's raided in the past year, but Chain Heal - Spell - World of Warcraft and it's improvements through talents (Improved Chain Heal - Spell - World of Warcraft and Tidal Waves - Spell - World of Warcraft)are extremely good and will make at least one Resto Shaman desirable to any raid. The mechanic of the spell (automatically bouncing to heal the lowest HP target in range) makes it irreplaceable and even better in WotLK.

-Cleanse Spirit - Spell - World of Warcraft gives the Shaman a one button debuff remover and adds in Curse removal. This will effectively lighten the load on Mages to decurse on certain fights (and let them DPS).

Warlock (Affliction):

-Affliction Warlocks are currently "buff bitches". Their DPS is miserable but they bring situational and often powerful buffs. I'm not sure how their DPS will shape up in WotLK but they at least have a new buff. Frailty - Spell - World of Warcraft will moderately boost physical damage giving the raid an extra 160 ArPen.

-They still have Shadow Embrace - Spell - World of Warcraft and Malediction - Spell - World of Warcraft. Note that all of these Warlock buffs and debuffs are raid-wide, however the Affliction Locks group position will probably again depend on the damage they are capable of putting out and whether they are pigeonholed into the "tank group imp buffer" slot.

Warlock (Demonology):

-Demonology in TBC is currently the a) Pvp or b) spec 21 points so you can not use your pet spec. This will change in WotLK due to the new Demonic Sacrifice [NYI] - Spell - World of Warcraft talent. This means that Demonology will be a primary damage dealing class with a pet, they do get a new useful raid buff in Demonic Pact - Spell - World of Warcraft which will be very desired in a caster-heavy raid.

Warlock (Destruction):

-Destruction brings one huge buff to the raid. Improved Shadow Bolt - Spell - World of Warcraft. With the introduction of DKs there is more shadow damage being done in the raid and this talent, which is currently very good, will be even more useful in WotLK.

Warrior (Arms):

-Blood Frenzy - Spell - World of Warcraft and now Trauma - Spell - World of Warcraft add a significant amount of raid damage, the latter being new in WotLK, will make this class even more beneficial to a raid (and to Rogues using Rupture and Feral Tanks/DPS using Lacerate).

Warrior (Fury):

-Commanding Presence - Spell - World of Warcraft is a significant buff to Battle Shout, it is, however, easily accessible to the Arms tree being only a Tier 3 talent. Other than that the Fury Warrior brings very little synergy to a raid. Although, looking at the new talents, perhaps the DPS of a Fury Warrior will return to it's pre-TBC glory days. It's possible that a Fury Warrior could Sunder Armor if there was a lack of Protection spec'd Warrior Tank in the raid, however, as noted in the Rogue section of this post, Improved Expose Armor is a superior option.

Warrior (Prot):

-The Prot Warrior brings some new tools to WotLK raiding (while still having the benefits of Battle/Commanding Shout and the Sunder Armor debuff). Starting with Vigilance - Spell - World of Warcraft, a skill that can be used on any raid member, but is very unique. In WotLK, many of the threat reduction buffs have been removed, making this skill much more powerful. The secondary effect of refreshing the somewhat long cooldown on Taunt when the target is attacked could prove invaluable to a raid.

-Safeguard - Spell - World of Warcraft is effectively a targetable Shield Wall ability that lasts 6 seconds and can be used every 25 seconds. Another almost irreplaceable skill.

-The new 51 point talent, Shockwave - Spell - World of Warcraft, is a 4 second AoE cone-effect stun. A few of these AoE stuns have been introduced in WotLK but this gives the Warrior a unique threat talent.


I have to go for now. I plan on adding more to the discussion later by comparing the relative buffs and debuffs that each class brings to a raid and also the ones that they benefit from most. Also I plan to draw up some theoretical raid/party combinations to maximize synergy. Please correct any mistakes I've made or add anything that I may have missed.

edit: Fixed some errors.

Improved Devo Aura (a Holy Pally or Prot Pally can pick it up) gives 3% more healing and 1807 armor (about ~5% melee damage reduction) to the raid assuming they are in a 40 yard range of the Pally.

The Blood Aura only shares heals on the DK caused by DK abilities, not any heals on the DK. Given that the powerful DK heals at the moment are currently as follows:

Vendetta - Works the DK kills a target for xp or honour.
Blood Presence - 4% of DPS.
Death Strike - When on a target that dies soon after, like how shadowburn returns a shard.
Scent of Blood - Works when the DK is hit.
Rune Tap, Imp. Rune Tap: 10-14.5% health return.

1 of the 4 health returns wont give as much health to the party when the DK is not tanking (and you wont be tanking in Blood Presense/Aura), and two others when the DK is not killing things often, you are left with sharing default Blood Presense healing, which is not going to be that significant.

It may be changed in the future to be more useful, but at the moment Blood Aura looks like ImpLotP or worse.

I am not sure if things like ImpLotP will count as heals caused by the DK when they proc it. If so then stacking auras and buffs that cause self-heal may improve the power of Blood Aura.

As I read the talent it is dependant on the caster's crit rate, not the druid's. So it will vary depending on the class.

At the moment it looks like Hunters, Feral Druids, and Blood DKs will give reasonable Melee Party buffs, while Moonkin and Ele Shamen will do the same for Casters. I think we can expect a fair bit of change though, given how mixed up the choices between raid and party buffs are at the moment.

I'd suppose though with the new talents like Enlightened Judgements and Judgements of the Pure, that holy paladins will be interested in maintaining a judgement rotation, with or without a retribution paladin? So you can at least be sure that JoW and JoL will always be up.