Arena play is vastly different from other PvP in the game. Before the battle starts, you have 1 minute of arena preparation, where spells cost 0 mana/rage/soul shards, and this is the time to buff up your team. You also won’t know the makeup of your opposition until they come up on your screen (although on smaller battlegroups you can often guess depending on how long you have queued for).
The two different arenas present different strategy opportunities.
Nagrand Arena
Nagrand is wide open, and has 4 pillars behind which characters can hide to prevent spells/effects hitting them. This means that while a mage may not be able to hit you with a spell, you also won’t be able to heal/be healed from behind the pillars.
Opening the battle, a commonly used tactic is to run straight behind the pillar on the left. This will give you time to work out exactly what kind of team your opposition has and plan your strategy accordingly. More advanced teams that can work well together (and are using voice communication) can mount up and ride straight toward the opposition, which can often have the effect of throwing them off significantly.
Other than that, Nagrand is a fairly simple arena. It is large and open, and there is little room to hide and no significant strategic positions.
Once a certain amount of time has passed, cyclones will spawn. These travel randomly around the arena, and hit players for around 2000 dmg, also sending them flying and knocking them back a significant distance. At the same time, powerups will spawn which allow stealth detection and slowly remove health.

Blade’s Edge
Blade’s Edge arena is vastly different to Nagrand. There are significant terrain issues and opportunities available with this arena that can frustrate many teams. There are two ramps, one on each side of the arena. A bridge connects the two ramps. Halfway down the bridge are two pillars which are separated by a small gap which can be easily jumped, provided you aren’t slowed in any way.
Most teams will immediately head towards their own ramp and wait to discern the makeup of their opposition. This strategy can sometimes be thrown by mounting up and heading straight to your opposition’s ramp. This will ensure that they are grouped up and can all be easily spotted, allowing a mage to get off a Nova on the whole team, or a warlock/priest to fear people away.
Also effective is dominating the pillars in the middle. Healers/ranged dps can jump on to the pillars before anyone can get near, ensuring that melee dps are going to have a rough time getting to them.
Hunters can have trouble in this arena due to the nature of the terrain. It is easy to get within their dead zone, and there are numerous line of sight issues with the ramps and pillars.
Mounting up is often the best strategy here – whether you want to put your healers on pillars, or just to ride to the opposition’s ramp – it is unpredictable (assuming you aren’t facing the same team repeatedly) and gives you an edge on your opponents.
There are also buffs which allow you to see stealth in this arena – they are located on the pillars.
2v2
2v2 is about bursting down your opponents, so certain classes will excel in this arena. Mages with presence of mind, destruction warlocks, and in some cases rogues are all very powerful.

Healing is not as essential in 2v2, simply because it is possible to burst down a healer (or even a dps class being healed) before much healing can help. This is especially true where you can shut down a healer without having to attack them – mages with counterspell, particularly against Paladin healers, are able to completely dominate. A focus macro works wonders here – set your focus to the healer when the match starts, then when you see a heal incoming, use counterspell without having to change targets.
If they have a healing class, healing debuffs can help immensely. Mortal Strike warriors and rogues with wound poison are excellent here – although both have weaknesses that can be easily exploited, and are probably more suited to the bigger arenas. Warriors are particularly weak solo, and almost require healing backup, preferably from a paladin.
Crowd Control is also extremely powerful in 2v2, simply because it reduces the effectiveness of a team by 50%. Cyclone, which is undispellable, is arguably the strongest form of CC in arenas in general, and particularly in 2v2s. Fear (against all but warriors) is also strong because it isn’t broken by damage, so you can fear a healer whilst you beat on the other player.
Paladins have Blessing of Sacrifice, which means that any team with a paladin will be immune to any crowd control that can be dispelled, and is broken on damage. It also means that a paladin is essentially immune to all forms of crowd control bar Fear and Cyclone, which makes them very strong arena healers.

Because of the nature of 2v2, which is focused more on burst, instants are the spell of choice, with Presence of Mind, Blastwave, Death Coil, etc. all being strong abilities that are difficult to compensate for. To be successful, you will need to spec for PvP – don’t expect to get a rating above 1600 with a Prot spec warrior, for example.

3v3
3v3 opens up many more opportunities for different classes, and requires much more adaptation to circumstances. While in 2v2, you can enter each battle with roughly the same game plan (CC the healer, burst the other, then work on the healer), the extra player in 3v3 situations creates a much greater chance of coming up against a team that will require a different approach.
While dual healers in 2v2 is probably a bad choice, multiple healers in 3v3 can be effective. This is where hybrids shine – elemental shaman that can backup heal, balance druids, and more can be very effective and powerful choices in 3v3 arenas. CC is still very powerful, again particularly Cyclone, but due to the extra player, and the potential for more dispellers, other types of CC may be removed much faster.
You will need a healer in 3v3. Gimmick teams, with say 3 PoM mages may have some success, but if a healer can react quickly, or you get resists, you are boned. Again, Paladins are very strong, but have particular weaknesses. Priests are capable if specced correctly with good gear (stacking stamina, healing, and then resilience are all important). Druids, with their focus on HoT’s may be used as healers, provided they can keep up with the DpS of the opposing team.
5v5
The ultimate arena, in terms of reward vs input, prestige, and difficulty. 5v5 arenas require excellent communication, coordination, and application. Two healers are almost essential, and it is much more beneficial if those two healers are different classes, simply for versatility. At least one offensive (priest/shaman) and one defensive (paladin/priest) dispeller will be of huge benefit to your team. A warlock with a felhunter can help but only in a limited capacity, especially when there are 5 possible targets.

Who you will target first depends on your group makeup and your opposition. Certain classes have very little defense and should be targeted first. If you have mostly casters, mages, especially fire ones, and warlocks are good targets. Melee- heavy groups will have trouble staying in range of mages, and in that case it is better to target shadow priests, shaman, or druids.
Distracting healers long enough to burst a player down is essential. Silencing Shot, and Counterspell, can completely shut down a healer, while Fear and other CC can help control them temporarily. Pets should be set to attack healers, as the damage they cause can help, and on some classes the interrupts are excellent.
Sheep (and all forms of CC), while often easily dispelled, is actually very important because it makes the paladin/priest spend mana and gives you 1.5 seconds where whomever you are attacking is not getting healed.
Priests should have Mass Dispel hotkeyed, and be ready to cast it IMMEDIATELY if they see a paladin bubble. Mages should do the same, but with counterspell, and use it on any healer, especially paladins, as they will be locked out of healing for 10 seconds, which is plenty of time to kill most classes.
Certain classes and specs are seen very often in 5v5. Arms warriors and Holy paladins are the most common 2 classes. Mages are next, with the rest of the classes being almost equal. Some specs are simply useless, but to do well in any area of the game you need to spec correctly for it.
Example Group Setups
These are some commonly seen/effective group setups that you can try out. They are by no means gospel, and every class can perform effectively in 5v5, but some have much more potential than others.
1.Holy paladin – healing only (Ret/Prot paladins are all but useless unfortunately).
2.Disc/Holy priest – healing and dispelling, both offensive and defensive. Blessed resilience is a must-have talent.

3.Arms warrior – 33/28 or any variation that includes MS and Death Wish. This provides excellent DpS (with amazing burst once some rage is built up), and nasty, undispellable debuff that really hurts the opposition healers.
4.Mage – frost for longevity or fire/Presence of mind for burst. Frost is probably better, because they can live far longer, and water elementals are free damage and are generally ignored. Counterspell is also important here.
5.Warlock – for Death Coil, Fears, and another silence if a felhunter is used. Demo specced will live the longest, and may be essential give warlocks are often targetted first. Destruction for burst Dps. An alternative is a Marksmanship hunter with silencing shot.
There are other options, though.
?Disc/Holy priest – healing, with blessed resilience for survival.
?Resto Druid – Also healing, but with more focus on Cyclone. Switching targets after 2 or 3 cyclones, so that the diminishing returns can reset and you can go back to the original target. Cyclone healers first.
?Elemental Shaman – a third healer, with good burst damage and 21 in Restoration for Nature’s Swiftness. Can also help heal if one of the other two healers goes down.
?Rogue – can lock down a healer solo. Very good against warlocks and to a lesser extent mages.
?Shadowpriest – to feed the healers mana, help with healing through Vampiric Embrace, and provide pretty good DPS.
Obviously the skill of the players will determine how effective you are, but 2 healers are basically a must.