Beast master
From Guild Wars Wiki
Beast Masters are Rangers who, instead of focusing on dealing damage through their bows, focus on strengthening their Pet, and use almost exclusively pet-oriented abilities. They were previously almost non-existent, but now thanks to numerous Updates and expansions (Factions, Nightfall, and Eye of the North) they are slowly gaining acceptance as a plausible character type.
Beast Masters are a cross between a Minion Master and a Warrior. They resemble Minion Masters because they bring another ally to the group without adding to the party limit. They resemble Warriors via their their pets, who, like Warriors, can either take an enormous amount of damage through the use of Defensive Shouts, or utilize many Pet Attack skills that are made to dish out large amounts of damage. The damage output can rival or even exceed the offensive capability of even some very high damage Elementalist abilities. Often a Beast Master takes a role that falls in between a pure offensive build and a defensive build.
[edit] Common abilities used.
Some common Shouts (Or Skill, in the case of 
Feral Aggression) used in a Beast Master skills include:
Defensive Abilities
Call of Protection is the most common defensive ability for pets of all, tied with 
Symbiotic Bond, as few abilities can compete with Call of Protection's base damage reduction.
Symbiotic Bond is generally used if the Beast Master prefers a defensive role for their pet, most commonly used in a Beast Master build known as the 'Tank Master.'
Offensive Abilities
Feral Aggression is used in a role where they want the pet to be dishing out the most damage possible, though many were turned away from it when Feral Aggression was nerfed.
Call of Haste allows the pet to move from target to target quickly, alongside the pet's base 20% movement speed increase, and conveniently dealing bonus damage in the process, effectively moving 45% faster than a player and receiving the IAS bonus as well, unconditionally.
Enraged Lunge is the most common pet attack used, partially because it has the largest + damage bonus of any Pet Attack, and at level 13 Beast Mastery or higher, it requires only 3 other Beast Mastery abilities to include the full damage bonus of 80, higher beast mastery affecting the damage bonus when the recharging requirement of 3 skills isn't met, and the pet's base damage improving Enraged Lunge's damage further when the 3 recharging skill requirement has been met.
Brutal Strike is generally used when a Beast Master does not wish to use Enraged Lunge as their elite ability, and comes in as the second highest + damage pet attack skill at +74, though has less controllable conditional requirements to meet the +damage bonus than Enraged Lunge.
Other Abilities
Heal as One is arguably the strongest healing ability a beast master can use, as it can resurrect the pet, and heal you, even when it resurrects the pet, which effectively performs 3 functions at once. Some are turned away by the fact it costs the ranger their elite ability though.
Comfort Animal, when not using Heal As One, is the only way for a beast master to both heal and resurrect their pet, though does not take up the elite ability.
Companionship is also useful to heal yourself or your pet conditionally based on who has the lowest health, but does not provide the ressurection that the two above skills do, though it is only worth the risk when a Beast Master has ensured that the pet will never be defeated, even when you are dead, in the case of Symbiotic Bond users.
Otyugh's Cry, now a welcome ability within the beast master community, crosses the line of pure offense and defense, as your pet gains an additional 24 armor, and cannot be blocked throughout the duration.
[edit] Strengths
Beast Masters, like Minion Masters, function as a living build - though instead of summoning up to 10 disposable minions, which are impaired by requiring corpse exploitation, they lack the ability to have numerous creatures following them, instead, having a single, powerful ally, that does not need corpse exploitation to function. They only need one of two skills - Call of Protection and Symbiotic Bond, to become one of the most effective tanks in the game, and are able to deal incredible damage, and through the use of several high damage skills/bufs, particularly Enraged Lunge and Feral Aggression, they also are one of the most effective damage dealers available. A skillful beast-master can turn both general PVE into a surprisingly painless task, since they conform to the general demand of PVE - high defense and damage, and dominate the grounds of general PVP, since few consider the pet a threat, and have some very PVP based buffs - Call of Haste and Otyugh's Cry, in particular. Although their ability to body block is limited compared to a Minion Master, Beast Masters have more control over their pet, and it does not become hostile to all when a Beast Master dies, unlike a Minion Master. Alongside Minion Masters, they also have something no other character can do - perform an action, such as resurrecting a party member, while being able to deal all their primary damage at the same time. Their primary tool, the Pet, does not suffer from Death Penalty in PVE as well, meaning they can stay out of danger and know that their pet will not be harmed by numerous deaths.
[edit] Disadvantages
The primary drawback is that while a Ranger may have a powerful Pet that deals the highest damage of most build types, and have the most defense, this comes at the price of suffering the limitations melee attacking characters suffer from, and the ranger is most likely to have a ranged weapon which has damage that cannot compare to the damage their pet can do. The Pet also suffers from being considered an 'ally' so certain skills will not affect it, and opposing AI consider pets of second importance compared to players, making them less useful tanks for large groups. Although for some it may not be an issue, PUGs in particular tend to not understand that Beast Mastery has become a character type that can challenge the warrior's ability to deal damage and tank. Although they have an additional ally to body block, they must needlessly sacrifice two skills at the very least to heal themselves, their pet, resurrect it, and make sure the animal stands by their side, in the case of Charm Animal. Pets, like Minions (though to a lesser extent compared to minions) suffer from AI algorithm, meaning a build that requires special timing is less plausible for a Beast Master, and although it is more advanced than minion AI, it is not on par with the AI of heroe's - they may needlessly become stuck behind certain NPCs and objects, do not flee from AOE, and only respond to attacks when the attacker is almost right next to the character, or if the Beast Master is attacking. Summing up the various faults of pets; they receive death penalty in certain PVP areas, such as Random and Team Arenas, and generally do not receive morale boosts in most areas of PVE, save for some select areas, such as the giants of the Thirsty River, and the very last non-elite mission in Nightfall.
