A team composition nearly identical to 2345 with the Mage slot filled by what originally was a Felguard Warlock but also seen with SL/SL Warlocks.
Although the joke about the 2345 comp is in key mashing, 2346 is a tongue-in-cheek reference to the former. Using generally the same strategies as 2345, this comp plays slightly more defensively because it no longer has the burst potential from Shatter. Felguard Warlocks usually have lower survivability and are often first targets for offensive-minded teams (hence the switch of some to SL/SL).
A team composition with one healer of any class and any four classes specced to DPS
Considering the simplicity of the composition, the idea is to quickly kill one target at the start of the match. Often criticized for being notoriously easy to play because it only needs to focus fire one target, 4-DPS is the team composition of the most popular multi- or quad-boxing class, the Elemental Shaman. A quad-boxing Shaman can easily put out ridiculous burst damage with four Nature's Swiftness / Elemental Mastery / Chain Lightnings on one target. Against 2345 and 2346, a 4-DPS team usually goes for a Warrior in Berserker Stance because of the 10% damage debuff.
One 4-DPS subtype is the JAC or Jolly Asian Clams, with a specific class composition of a Frost Mage, Shadow Priest, Subtlety / Shadowstep Rogue, Affliction Warlock, and a Restoration Shaman healer. This was named after the team that first ran this comp past 2200 rating with most members wearing PvE gear.
A team composition consisting of three melee DPS and two healers, usually a Mortal Strike Warrior, a Shadowstep Rogue, and an Enhancement Shaman. Can also apply to 3v3 teams with two melee classes such as Warrior / Warrior or Warrior / Rogue and a healer.
I discussed this in an earlier Blood Sport, where the general idea behind the comp is to train one target, usually a cloth-wearing class susceptible to armor penetration. Although triple melee can consist of different melee classes, sometimes having two Warriors or even a Retribution Paladin, the comp above was popularized by Serennia, who tried to have it named Trifecta. Cleave teams benefit from having a Shaman because of Windfury Totem, Bloodlust / Heroism, and Purge against Blessing of Protection.
An important mechanic to understand in PvP, Diminishing Returns usually applies to most Crowd Control and movement imparing or immobilizing spells and works in the following manner: the first application of the spell works to its full duration -- all Crowd Control spells in PvP have a maximum duration of 10 seconds. A second spell of the same category (e.g. Stun, Root, Fear, etc.) used on the same target will have its duration reduced by 50%. The third spell will have its duration reduced by 75% while a fourth spell will render the target immune to all spells of the same category. A target must be free of any spells within a particular category for 15 seconds in order for Diminishing Returns to reset.
A team composition featuring one or more of the classes with mana draining abilities -- Hunter, Priest, or Warlock and capitalizes on those abilities as a strategy
Amanda Dean detailed the Drain Train in an older Blood Sport. In a nutshell, drain teams control a match long enough to burn a target healer or DPS' mana to near empty before going on the offensive.
A team composition of Druid, Mage, Rogue, Priest, and Warlock
Termed Eurocomp because it originated in the European Battlegroups, Eurocomp focuses on controlling the match. The particular spec of each class isn't as important -- although it obviously helps -- because the idea is to rely on the superb crowd control abilities of each class. A well-played Eurocomp is extremely difficult to beat because it severely disrupts any strategy, with crowd control breaking the burst potential of a 2345 or 2346, for example.
Gib or Instagib
To kill in a fast manner, usually as a target of focus fire
The term is borrowed from first-person shooters, where killed targets explode into gory body parts referred to as 'giblets', as in the chicken parts. Instagib is a portmanteau of instant and giblets, usually used to refer to targets who die within a few seconds. The strategy of most 4-DPS teams, for example, revolve around instagibbing the opposing team's Warrior.
Line of Sight
An extremely important mechanic in PvP as all spells in the game require that the target must be within line-of-sight in order for the spell to be cast. This allows players to use objects in Arenas, such as pillars, to break casting. It's important to note that LoS does not break a channeled spell that has already landed.
A way to remove crowd control or other harmful effect.
This usually refers to abilities on long cooldowns such as Will of the Forsaken that removes the player from harm. Usually spammed over vent to inform teammates that an effect such as Cyclone will go the full duration, thus allowing them to adjust their play to accommodate a CC'd or otherwise impaired member.
Moving out of range of healers
A player usually overextends when they move ahead to scout the opposing team. Oftentimes, this applies to Druids or specially Rogues who attempt to Sap an opponent and get the opener on a target. Overextended players are excellent targets, particularly for high burst DPS teams. The Arena maps will have areas where overextended players are not only out of range but also out of LoS of their healers, such as the pillars in Nagrand or beyond the tomb in Lordaeron.
To remove pressure from a teammate, or the PvP equivalent of a taunt
Peeling is an important skill to learn that only the best Arena teams master, where the use of every ability such as snares, roots, other forms of crowd control or even just the sheer pressure of raw damage eases the pressure on a teammate. A large part of the success of team Orz, champions in MLG Orlando, is the ability of their members to peel targets off their druid, Hafu.
A team composition consisting of Rogue, Mage, and Priest in the 3v3 format
Amanda covered RMP in an earlier Blood Sport, featuring one of the most popular and effective team compositions in 3v3. The team relies on the superior control abilities of all three classes combined with high burst and healing support. RMP is used by many professional Arena teams, such as Korea's Council of Mages, who won the Worldwide Invitational tournament.
To remove an opponent's buffs
It's important to remove a target's buffs in order to leave them at their most vulnerable. Abilities that remove buffs such as Purge, Dispel Magic, Spellsteal, and even a Felhunter's Devour Magic are critical to stripping a target. A player without any buffs whatsoever is an easier target to kill.
To focus on one target for the better part of a match OR to focus on one thing exclusively
This term can refer to focus firing on one target, usually applied to teams with Rogues, who must Tunnel Vision their target because of poison applications. It can also refer to a bad habit of focusing solely on one task to the exclusion of other important tasks, such as a Shaman who has Tunnel Vision on Purge and forgetting to heal teammates.
Turtle or turtling
To play extremely defensively, usually by staying near or at the starting area
Borrowed from Warsong Gulch, where defensive teams 'turtled' in their bases, teams who turtle sometimes have scouts such as a Rogue or Druid who more than likely overextend. Turtling is most common and easiest to do in the Ruins of Lordaeron, where teams can effectively stay out of LoS by hugging the walls beside the opening gates.
To focus fire or assault a single target with all offensive team members
A term borrowed from StarCraft, named after the Zerg unit Zergling, which gets strength from its numbers. A zerg rush refers to a constant single-minded assault, and applies to Arenas when all possible team members rush towards a specific target. Warlocks are a popular zerg target.
Do you enjoy Arenas or want to learn more? Read Blood Sport, WoW Insider's column dedicated purely to Arena PvP. Learn more about the dreaded Cleave team composition or how to go about making (or breaking) a Drain Team. You can also find guides on how to gear up for Season 4 or take a break from Arenas altogether.