View source for Hero behavior/Unexpected behavior

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| style="text-align:left; width:100%;" | <big>'''Before posting here:'''</big> 
Please confirm potential issues on the [[talk:Hero_behavior/Unexpected_behavior|talk page]], so that we can provide accurate data. When identifying problems, please include the location where the problem occurred, the name of NPC using the skill, and the difficulty (hard mode or normal). See also: [http://wiki.guildwars.com/index.php?title=Talk%3AHero_behavior%2FUnexpected_behavior&action=historysubmit&diff=2476886&oldid=2473784 this post] by developer [[Joe Kimmes]].
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This article is the counterpart of [[Hero behavior]] page. It gathers research made by users, basically stating how the hero [[AI]] activates skills different than a player would.

Questionable edits may be moved to the talk page for further debate.

== Unused skills (unless forced)==
''Skills that AI never uses at all, unless forced to do so. A player will have to micromanage their skills monitor.''

* {{skill icon|Rending Aura}}: AI doesn't use skill at all.  Fix: Make hero use skill with the same frequency as it does for other offensive flash enchantments.
* {{skill icon|Eremite's Zeal}}: AI doesn't use this skill unless they're already enchanted, as a remnant of previous functionality. Fix: Make hero use skill regardless of being enchanted.

== Limited-use skills ==
''Skills that AI do not use to their full potential.''
* {{skill icon|"I Will Avenge You!"}}: Hero uses when one corpse in earshot. Would be more effective if waited for higher number of deaths, e.g. if a pet has low hp and is likely to die soon, it would be better to wait.
* {{skill icon|"The Power Is Yours!"}}: Heroes only use skill when an ally is actively regenerating energy.  Fix: Make hero use skill as soon as it is available.
* {{skill icon|Rodgort's Invocation}}: Hero only use this skill when the target is at or below 20% HP.  Fix: Remove this restriction.  Use skill as normal.
* {{skill icon|Vampiric Gaze}}: Hero only use this skill when the target is at or below 50% HP.  Fix: Remove this restriction.  Use skill as normal.
* {{skill icon|"Watch Yourself!"}}: Hero doesn’t use skill if other allies have skill effect active on them.  Fix: Make hero use skill as soon as it’s available regardless of having any allies that are affected by it.
* {{skill icon|Icy Veins}}: Hero doesn’t use skill on same target if another ally is also casting {{skill icon|Icy Veins}}.  Also doesn't cast on a target with a preexisting{{skill icon|Icy Veins}} hex.  Fix: Make hero use skill for damage regardless of if another ally is casting {{skill icon|Icy Veins}} and/or if target is hexed by {{skill icon|Icy Veins}}.
* {{skill icon|Glyph of Elemental Power}}: Hero doesn’t cast any spells from non-elemental attributes while this skill is active.  Fix: Allow hero to cast spells from non-elemental attributes while this skill is active.
* {{skill icon|Finale of Restoration}}: Only uses skill on target 90% HP or lower and infinitely renews skill regardless of remaining duration.  Fix: Use skill to try to apply to entire party and important allies like pets and mission/quest important npcs.  Only renew skill after expiring.  Similar to how AI uses {{skill icon|Tainted Flesh}}.
* {{skill icon|Blazing Finale}}: Hero only uses skill on an ally actively being attacked by a melee enemy.  Fix: Make heroes use skill on allies most likely to be in melee proximity to enemies.
* {{skill icon|Signet of Sorrow}}: If target is not near a corpse or has a dead pet, Hero doesn’t use skill unless target is at or below 50% HP.  Fix: Make hero use skill regardless of target HP or to only use skill if target is near a corpse or has a dead pet.
* {{skill icon|Depravity}}: AI doesn't use spell on Master of Healing and Master of Enchantments npcs in Isle of the Nameless even though they have spells.  Fix: Make hero use skill on foes that have spells.
* {{skill icon|Enduring Toxin}}: Hero doesn't attempt to cast unless foe is already moving.  Should be using skill on recharge.
* {{skill icon|Shameful Fear}}: Hero doesn't attempt to cast unless foe is already moving.  Should be using skill on recharge.

=== Additional effects ignored ===
''Skills that AI only use for their [[initial effect]]; but ignore subsequent and/or [[end effect]]s.''
* {{skill icon|Fierce Blow}}: AI uses for the damage bonus, attacking targets without Weakness condition, wasting the chance to inflict Deep Wound.
* {{skill icon|Overbearing Smash}}: AI uses for the damage bonus, doesn't knockdown first before skill to inflict Dazed condition, wasting the chance to inflict Dazed.

== Inefficient skills ==
''Skills that AI fails to time properly and/or use too often until they completely run out of [[energy]].''

=== Inappropriate spamming ===
''AI spams them until their energy is completely depleted.''
* {{skill icon|Patient Spirit}}: AI casts it as a heal but the ally will still be targeted by another heal skill before Patient Spirit ends, which may cause over-healing (wasting energy and time). Although it is still worth the alternative in case target ally is being spiked. The problem doesn't fall on this skill by itself.

=== Chaining ===
* {{skill icon|Defensive Anthem}}: Hero doesn’t chain skill properly, just overlaps it or refreshes it once it falls off a single party member.  Fix: Make heroes chain skill in the same way they can chain {{skill icon|Aegis}}.  As long as a single ally has Defensive Anthem active on them, don’t use it till all copies are expired.

=== Failure to re-apply to maintain benefits ===
''Skills that a player would use before they end such that they gain the cumulative benefit.''

=== Wasted opportunities ===
* {{skill icon|Berserker Stance}}: The AI wastes it by using a skill before building adrenaline.
* {{skill icon|Resilient Was Xiko}}: AI drops the ashes if they're under the effects of a single condition, even though the skill can remove more than one condition when dropped.
* The AI will ignore [[effect stacking]] cap limits. E.g. the AI will use [[speed boost]] shouts: {{skill icon|"Charge!"}}, {{skill icon|"Incoming!"}} and {{skill icon|"Fall Back!"}} at once even though it would be more efficient to use them sequentially.

=== Skills used for right purpose, but inefficiently ===
* [[Item_spell#List_of_item_spells|Item spells]] can cause the AI to close-in to their targets at melee range, which can put mid and back-liners to dangerous situations.
* {{skill icon|Explosive Growth}} and {{skill icon|Spirit's Gift}}: AI only uses these during combat as opposed using and maintaining it before and outside of combat, in the same manner as {{skill icon|Boon of Creation}}. 
* {{skill icon|Signet of Binding}}: AI also steals ranger spirits, gaining limited benefit other than another body to take damage, since such spirits' effects are global.
* {{skill icon|Pious Fury}}: AI just uses skill and doesn't consider using a teardown enchantment to get the maximum duration.
* {{skill icon|"We Shall Return!"}}: AI doesn't use skill when out of combat to revive dead allies.
* {{skill icon|Whirlwind}} AI runs in to use skill on foes in range, where it would be preferable for it to use it defensively when melee foes get nearby of their own accord.

=== Fatal damage [[Negation effect|negation skill]]s ===

== Misused skills ==
''Skills that AI use without meeting requirements, wrong targets and/or unnecessary times.'' 
* '''General''': AI uses [[Bleeding]], [[Disease]] or [[Poison]] skills on non-[[fleshy]] foes (e.g. {{skill icon|Poison Arrow}} and {{skill icon|Rotting Flesh}}).
** AI uses [[condition]] skills on [[spirit]]s which are immune to all except [[burning]] (e.g. {{skill icon|Throw Dirt}}).
* '''General''': Dervish behavior fix: {{skill icon|Intimidating Aura}}, {{skill icon|Veil of Thorns}}, {{skill icon|Armor of Sanctity}}, {{skill icon|Ebon Dust Aura}}, {{skill icon|Vow of Strength}}, {{skill icon|Grenth's Grasp}}, {{skill icon|Onslaught}}, {{skill icon|Zealous Vow}}, are to be strongly avoided for use in tear down effects, prioritize using these skills first and then covering with other enchantments that are meant to be torn down.
* '''General''': General AI behavior fix: Does not seem to use buff skills like Brutal Weapon on allies such as pets.  AI should use buffs on allies after appropriate party members are buffed.
* '''General''': General AI behavior fix: Allow overlapping use of skills of the same name on a target, unless their overlap would produce a worse result.  Allow heroes with the same equipped skills to activate the same skills at the same time.
* '''General''': Ranger behavior fix: make hero maintain all preparations in the same manner that they already maintain apply poison.

== Unexpected due to player's inexperience ==
''Skills which seem to malfunction by players with poor AI knowledge.''
* {{skill icon|Arcane Mimicry}}: Commonly seen with a [[UA]] partner. Some players will not want the AI to re-copy UA while the HB monk already is maintaining it, but the opposing alternative would require the player's micromanagement which would be much more tedious.

== Verification requested ==
''Skills were listed prior the last article overhaul without back-up support and need to be double-checked to confirm their statements:''
* AI is unable to chain skills properly, e.g. [[glyph]]s with spells, forfeiting the combo's advantage (or at least not using it to its full potential). {{verify|is this still true after the AI update (remove if not}}

== Notes ==
* Heroes and [[henchmen]] use the same [[AI]] <small>([http://wiki.guildwars.com/index.php?title=Feedback_talk:Joe_Kimmes&diff=prev&oldid=1710292#New_henchman_bars source])</small>, so this article also applies to henchman behavior (except for ''Modes'' and ''Forced skill use'', which are not available to them).
* Heroes of the same profession use the same AI; they are interchangeable for all practical purposes. <small>(See: [[Talk:Hero behavior#Different AIs?|the talk page]].)</small>

== Trivia ==
* [[ArenaNet talk:AI bugs]] was the old wiki page to report AI bugs until September 2, 2009.

=== Historical upgrades ===
* [[Feedback:Game_updates/20190205|2019, February 5th]]:
** Implemented change in AI to a large amount of skills.
* [[Feedback:Game updates/20120301|2012, March 1st]]:
** Reverted the last adjustment to the aggro range of heroes and henchmen.
** Adjusted the speed with which [[Assassin]] heroes execute [[skill chain]]s.
* [[Feedback:Game updates/20120216|2012, February 16th]]:
**The update changed skills that were listed in this same page under ''Missed-use'' and ''Unused-use'' sections by that time, the improvements had no specific details provided. <small>([[Talk:Hero_behavior/Unexpected_behavior_Archive_1#2.2F16_Update]])</small>. This page has been overhauled ever since.
* [[Game updates:January 2012|2012, January 5th]]: 
** Overhaul of the Elementalist profession led to [https://forum.guildwars.com/forum/forums/gamebugs/Doublecast-Skills unpredictable AI behavior].  
** Adjusted the [[AI]]’s usage of: [[Double Dragon]], [[Gust]], [[Mirror of Ice]] and [[Stone Sheath]].
* [[Feedback:Game_updates/20110303|2011, March 3rd]]:
** Added Mercenary Heroes to the game.
* [[Feedback:Game_updates/20091029|2009, October 29th]]:
**Removed heroes from [[PvP]] (with the exception of [[Isle of the Nameless (PvP)]] and [[Training Arena]]). According to [[Andrew Patrick]], removing the ability to have heroes in the party for [[Zaishen Challenge]] and [[Zaishen Elite]] ''"was an unintended side-effect of removing them from other PvP formats."'' ([http://wiki.guildwars.com/index.php?title=Feedback:Bug_reports/Miscellaneous_bugs&diff=prev&oldid=1862538#Can.27t_use_Heros_in_the_Zaishen_Challenge_and_Zaishen_Elite_areas source])
* [[Game_updates/20090618#AI_Updates|2009, June 18th]]: 
**AI updates to Heroes and Hard Mode NPCs.
* [[Game_updates/20080807#AI_Updates|2008, August 7th]]: 
**AI updates to Heroes and Hard Mode NPCs. 
** The AI does not always activate skill as they change; some skills are still used as their version prior the game update (e.g. [[Healing Burst]] as a Touch skill).
* [[Game updates/20070831|2007, August 31st]]: 
**New heroes introduced via [[Guild Wars Eye of the North|Eye of the North]] expansion.
* [[Game updates/20061025|2006, October 25th]]: 
**Heroes introduced to Guild Wars via [[Guild Wars Nightfall|Nightfall]] campaign.

== See also ==
Research articles created by users:
* [[User:Infinite/Hero AI|Infinite's Warrior Hero research]]

[[Category:AI behavior update| ]]
[[Category:Hero guides|Hero]]