Hero behavior/Unexpected behavior

Before posting here: Please confirm potential issues on the 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: this post by developer Joe Kimmes.

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.

• Rending Aura: AI doesn't use skill at all. Fix: Make hero use skill with the same frequency as it does for other tear down skills.
• Eremite's Zeal: AI doesn't use skill at all. Fix: Make hero use skill when enemies are in earshot.
• Wither: AI doesn't use skill at all. Fix: Make hero use skill.

Limited-use skills

Skills that AI do not use to their full potential.

• "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.
• "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.
• Rodgort's Invocation: Hero only use this skill when the target is at or below 20% HP. Fix: Make hero use skill with the same frequency as other Elementalist spells.
• Flail: Hero only uses skill after autoattacking a target that is knocked down. Fix: Make hero use skill when it is available, especially before using a skill that causes adrenaline loss e.g. Hammer Bash.
• "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.
• Anthem of Weariness: Hero doesn’t use skill to maintain refrains. Fix: Make hero use skill in the same manner as Anthem of Flame.
• Icy Veins: Hero doesn’t use skill on same target if another ally is also casting Icy Veins. Also doesn't cast on a target with a preexisting Icy Veins hex. Fix: Make hero use skill for damage regardless of if another ally is casting Icy Veins and/or if target is hexed by Icy Veins.
• 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.
• 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 Tainted Flesh.
• 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.
• 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.
• 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.

Additional effects ignored

Skills that AI only use for their initial effect; but ignore subsequent and/or end effects.

• Fierce Blow: AI uses for the damage bonus, attacking targets without Weakness condition, wasting the chance to inflict Deep Wound.
• 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.

• 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

• 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 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

• Berserker Stance: The AI wastes it by using a skill before building adrenaline.
• 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: "Charge!", "Incoming!" and "Fall Back!" at once even though it would be more efficient to use them sequentially.

Skills used for right purpose, but inefficiently

• 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.
• Explosive Growth and 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 Boon of Creation.
• Signet of Binding: AI also steals ranger spirits, gaining limited benefit other than another body to take damage, since such spirits' effects are global.
• Pious Fury: AI just uses skill and doesn't consider using a teardown enchantment to get the maximum duration.
• "We Shall Return!": AI doesn't use skill when out of combat to revive dead allies.
• 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.

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. Poison Arrow and Rotting Flesh).
  • AI uses condition skills on spirits which are immune to all except burning (e.g. Throw Dirt).
• General: Dervish behavior fix: Intimidating Aura, Veil of Thorns, Armor of Sanctity, Ebon Dust Aura, Vow of Strength, Grenth's Grasp, Onslaught, 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.

• 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. glyphs with spells, forfeiting the combo's advantage (or at least not using it to its full potential). ^{[verification requested]}

Notes

• Heroes and henchmen use the same AI (source), 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. (See: the talk page.)

Trivia

• ArenaNet talk:AI bugs was the old wiki page to report AI bugs until September 2, 2009.

Historical upgrades

• 2019, February 5th:
  • Implemented change in AI to a large amount of skills.
• 2012, March 1st:
  • Reverted the last adjustment to the aggro range of heroes and henchmen.
  • Adjusted the speed with which Assassin heroes execute skill chains.
• 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. (Talk:Hero_behavior/Unexpected_behavior_Archive_1#2.2F16_Update). This page has been overhauled ever since.
• 2012, January 5th:
  • Overhaul of the Elementalist profession led to unpredictable AI behavior.
  • Adjusted the AI’s usage of: Double Dragon, Gust, Mirror of Ice and Stone Sheath.
• 2011, March 3rd:
  • Added Mercenary Heroes to the game.
• 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." (source)
• 2009, June 18th:
  • AI updates to Heroes and Hard Mode NPCs.
• 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).
• 2007, August 31st:
  • New heroes introduced via Eye of the North expansion.
• 2006, October 25th:
  • Heroes introduced to Guild Wars via Nightfall campaign.

See also

Research articles created by users:

• Infinite's Warrior Hero research