Aggro

Some enemies aggro when players attack other foes they are allied with, indicated by crossed swords icon.

Aggro refers to gaining, controlling and losing the aggression of hostile NPCs and any related mechanics in general.

Generic NPC enemies will typically select targets based primarily on a range calculation, meaning the character or allied NPC such as minion or pet closest to the hostile NPC will hold its attention. Additionally, some NPCs are stationary, while others have a defined movement path or a defined aggression territory.

There are additional factors which influence enemy aggression, and some creatures have unique aggro conditions and mechanics. For example, many raid and strike mission boss encounters have special Fixated effects, designed to provide a controllable aggro mechanic.

Threat

While in combat, player characters and other creatures will generate threat against enemies. The player or creature with the highest threat will gain the aggro of the enemy or enemies if there are no other factors that may direct the enemies' aggro elsewhere (see below).

Threat table

Most hostile NPC enemies maintain an internal threat table which functions on a simple priority-queue principle: The head of the queue is occupied by the player that has the most threat and the tail of the queue is occupied by the player that has accumulated the least threat. The amount of threat does not only include damage-per-second; many NPCs are attracted to certain conditions, such as proximity, total damage dealt over time, or if a player has a high amount of toughness.

Gaining threat

There are multiple ways to increase threat generation towards an enemy. These are typically cumulative. The actual aggro effectiveness of various threats depends on multiple factors which can vary greatly between enemies.

• Having the highest score in a certain defensive attribute such as toughness.
• Being the closest or farthest target (e.g. Captain Mai Trin's pistol shot is usually aimed towards the person farthest from her).
• Dealing the most damage or attacks in a certain amount of time or in total (e.g. the Thaumanova Anomaly).
• Having the lowest character level (Mastery level is not counted).
• Attacking a related enemy, for example part of the same event (e.g. attacking a Toxic Knight during a Toxic Offshoot event can cause a Toxic Nimross to rush to the location).
• (Rarely) Being in downed state. (e.g. Legendary Bandit Executioners will focus downed state players, becoming temporarily vulnerable to crowd control skills.) Such a high spike in aggro is very rarely seen.

Unconfirmed factors:

• Using a shield^{[verification requested]}
• Reviving a fallen ally^{[verification requested]}

Losing threat

Players who have gained unwanted threat or aggro can lose it in several ways. Effects can be cumulative or they can be ignored by specific enemies.

• Gaining Stealth will immediately drop aggro, but may not cause threat generation to decrease.
• Dealing less damage
• Moving far away or to a place enemies cannot reach
• Being downed^{[verification requested]}

Aggro and tanking

There are multiple ways to gain and hold the aggro of a hostile enemy. The actual effectiveness of each condition depends on the enemy creature's A.I. and other factors.

• Being  Fixated
• Using  Taunt (Does not work against enemies with a defiance bar)
• Individually scripted decisions and other mechanics. For example:
  • Giganticus Lupicus will pick a specific player and always teleport to him for the duration of the fight or the target's defeat.
  • Holding   Claim while fighting the Mursaat Overseer.
  • The Legendary Bandit Executioner will immediately head to a downed player to finish them.
• Having the highest score in a certain attribute, usually toughness.
• Being the closest or furthest target.
• Dealing the most damage or number of attacks in a certain time period.
• Having the lowest character level (Mastery level is not counted).
• Maintaining threat on the enemy (see above).

Enemies who no longer have aggro to any players or creatures will leave combat and either begin regenerating to full health or despawn until the encounter is properly reset.

Tanking

Tanking is often done to prevent dangerous enemies from downing less survivable characters or from defeating mission-crucial NPCs. Tanking in Guild Wars 2 does not require for a character to be a specific profession.

Tanking may also be a mandatory combat mechanic in certain encounters, for which players will need to prepare accordingly. Certain raid and fractal bosses in particular have highly specified conditions for which player they will focus on. Tanks are often required to make use of defensive skills and effects, positioning so that the battle is advantageous to the player's side, or perform other encounter-specific strategies and mechanics.

• Fixation — Some enemies will give a specified player the effect  Fixated. Fixation is defined randomly, upon a specific condition, or after a certain interval. While a player is fixated, the boss will follow this player and all attacks will be in their direction. If the fixated player becomes downed or dies, another player will become fixated.
  • Notable enemies: Slothasor, Legendary Dredge Power Suit, Legendary Rampaging Ice Elemental, Projections during the fight against Keep Construct, Mursaat Overseer, Samarog, Soulless Horror, Echo of the Unclean during the fight against Siax the Unclean and Siax the Corrupted
• Having the highest toughness — Some bosses will focus on the target with the highest toughness value. If another player gains more toughness during the fight, or if their main target loses enough toughness (or dies), they will switch to the next highest toughness value.
  • Notable enemies: Vale Guardian, Gorseval the Multifarious, Keep Construct, Xera, Deimos, Broken King, Eater of Souls, Dhuum, Twin Largos (Nikare and Kenut), Cardinal Sabir, Cardinal Adina
• Furthest target — Some enemies will choose the furthest player in the area and have some of their attacks go in their direction.
  • Notable enemies: Captain Mai Trin, Cairn the Indomitable
• Closest target — Some enemies will target the closest player within their area or the first one to approach it with certain conditions and have their attacks go in their direction.
  • Notable enemies: Qadim, Qadim the Peerless
• Random person — Some enemies will choose a random person in the area when the fight begins and have some of their attacks focused in their direction. Another player will be chosen if their initial target has died or after some other boss-specific mechanic.
  • Notable enemies: Giganticus Lupicus, Matthias Gabrel

See also

• Control
• Defiance bar