How to Beat Ansur in BG3: Lightning Pool Positions, Dragon Phase Patterns, and the 3 Builds That Survive

Quick Start: What You Need Before the Fight

Ansur is Act 3’s hidden dragon boss and a mandatory encounter for Wyll’s companion questline. Before entering the Dragon’s Sanctum, lock down these five points:

• Elixir of Lightning Resistance × 4 — Ansur’s entire kit is lightning damage. Without mitigation, even Phase 1 attacks are punishing.
• Arrows of Dragon-Slaying — available from vendors in Acts 2 and 3. They deal double damage to dragons and are the highest single-round damage burst available for physical builds.
• Grab the Helm of Balduran before combat — it sits on an altar behind Ansur’s corpse. The fight triggers when you interact with him, not the altar. The helmet is inaccessible once combat begins.
• Locate the three crystal pillars on entering the arena — scan the chamber edges before engaging. These are your only guaranteed cover positions during Stormheart Nova.
• Honour Mode: plan for two Stormheart Novas — Unrelenting Storm keeps Ansur at 1 HP and triggers a second Nova immediately. One pillar dash is not enough.

Verified on Patch 8. Values may change with future updates.

When NOT to attempt: Don’t enter the Dragon’s Sanctum under-levelled or under-geared. Ansur is a Level 17 Undead Dragon with 400 HP on Balanced — you should be Level 10–12 with Act 3 gear and at least one source of lightning resistance before engaging. If you don’t have Elixir of Lightning Resistance or the Protection from Energy spell prepared, clear Act 3’s lower-tier encounters first and restock vendors before returning.

How to Reach Ansur

Ansur is located in the Dragon’s Sanctum beneath Wyrm’s Rock Prison in Act 3’s Lower City. From the prison’s ground floor, head west until you find two dragon sconces mounted on the wall. Hit each with an electricity source — Wyll’s Eldritch Blast, a lightning cantrip, a Javelin of Lightning, or any electric arrow — to light both and open the hidden passage to the Wyrmway.

The Wyrmway contains four trials that must be completed before the Dragon’s Sanctum unlocks: Courage, Insight, Strategy, and Justice. The Strategy trial is the most punishing for impatient players — community reports indicate the puzzle resets permanently after more than two moves, so plan your solution before touching any piece.

Defeating Ansur is mandatory for Wyll’s companion quest, Tales of Ansur. Wyll doesn’t need to be in your active party when you kill the dragon — the quest resolves based on the kill, not attendance. Before heading to Ansur, check our BG3 Act 3 guide for time-sensitive quests that can fail if you trigger certain events in the wrong order.

Ansur’s Stats: Know What You’re Facing

The critical immunity: Ansur takes zero damage from lightning. Every lightning-typed spell — Thunderwave, Chain Lightning, Call Lightning, Witch Bolt, lightning-infused weapon enchantments — contributes nothing. Players who build into a Sorcerer or Tempest Cleric for this fight and lean on their signature element will feel it. Cold, fire, radiant, and physical damage all work normally.

On Tactician and Honour, Greater Wyrm’s Scales reduce every single hit by 4 damage [1]. Over a 30-attack fight that’s 120 damage absorbed — almost one-third of Balanced HP. Abilities that stack high damage per hit (Divine Smite, Arrows of Dragon-Slaying, Great Weapon Master) perform better here than sustained multi-hit abilities with low per-strike values.

Magic Resistance (Advantage on all spell saves) makes DC-based control spells less reliable than in most fights. If your build relies on Hold Monster or Banishment, expect the save to succeed noticeably more often than your DC suggests: Advantage roughly halves the fail rate (a 50% base fail chance becomes ~25% with Advantage). Damage output that doesn’t require a save — physical attacks, Wall of Fire, Hunter’s Mark — is more consistent.

Phase 1: Draconic Wrath and the Opening Turns

The fight opens with Ansur plus two Water Myrmidons — Level 11 constructs with 165 HP and AC 18 each [7]. Don’t focus the Myrmidons. Ansur’s Stormheart Nova (the fight’s first major event) deals area damage that hits them in the blast, effectively clearing them for free. Spending Phase 1 actions on Myrmidon HP delays the burst you need on Ansur before his flight phase and gains you almost nothing in return.

The one exception: if a Myrmidon is positioned near a chasm edge, Thunderwave or Repelling Blast (Eldritch Blast invocation) knocks it off the arena immediately at near-zero resource cost. A free 165 HP elimination is worth one bonus action.

Draconic Wrath is the fight’s defining reactive threat in Phase 1. Ansur gains this legendary action condition at the start of each round. The first time a character deals damage to him that round, he immediately retaliates with Lightning Breath — 12d6 lightning damage aimed directly at the attacker [1][3]. The condition resets each round, so only the first damaging hit per round triggers it. Missed attacks do not trigger the retaliation.

Three approaches neutralize this:

• Evasion (Monk level 7, Rogue level 7): Ansur’s retaliatory Lightning Breath requires a DEX save. With Evasion, a passing save deals zero damage and a failing save deals half — effectively making the reaction free to absorb [1].
• Flurry of Blows: Stagger (Way of the Open Hand Monk): The Staggered condition denies Ansur his reaction before it fires, protecting the attacker without needing to pass a save.
• Arms of Hadar: Spell that denies reactions outright if connected. Lower priority but available for Warlock builds [1].

Without one of these, open each round with your highest-AC character rather than your highest-damage dealer. The Draconic Wrath retaliation is a fixed 12d6 regardless of the attack that triggered it — the relevant question is which party member can best absorb up to 42 lightning damage as a consequence of the opening hit.

Ansur uses Multiattack (4d8+7 slashing + 3d8+7 piercing + 4d6 lightning, melee range) and standard Lightning Breath interspersed with repositioning flight. Keep spellcasters at 9m+ unless they have defensive tools, since Multiattack’s combined average of ~59 damage reaches most “safe” backstep positions if Ansur closes distance.

Stormheart Nova: The Fight’s Turning Point

At roughly half HP, Ansur activates Gather Power, taking flight and becoming resistant to all damage types for one turn [1]. He cannot take any other actions while this is active. The only counter during this window is the Stunned condition — a successful Monk Stunning Strike (CON save) cancels Gather Power entirely and skips Stormheart Nova. At CON +6, the save is not easy to force, but the payoff is worth the Ki spend.

If Gather Power completes, Ansur releases Stormheart Nova: 18d10 lightning damage that targets the entire arena. At average roll that’s 99 damage; maximum is 180. Most builds at standard Act 3 HP totals don’t survive a direct hit regardless of resistance.

What saves you isn’t lightning resistance. It’s the Ansur’s Ire condition.

Every character exposed in the arena carries Ansur’s Ire. Stormheart Nova only damages characters who currently have this condition — and it’s removed by taking cover. Stepping behind a crystal pillar removes Ansur’s Ire from your character instantly. When the condition icon disappears from your status bar, Nova passes over you without damage [1][6].

This matters because it changes the decision. You’re not looking for a pillar that “blocks” the blast — you’re looking for cover that removes a condition. Characters inside a Globe of Invulnerability or an Otiluke’s Resilient Sphere are also protected regardless of Ansur’s Ire, since those spells prevent the damage from a different angle [1].

Pillar mechanics in detail: Three crystal pillars sit at the arena edges. Reaching one removes Ansur’s Ire and applies Crystal Skin — elemental resistance for two turns, carrying into Phase 2’s lightning strikes [6]. If the party needs to be Hasted, cast the spell now while everyone is gathered at a pillar. Haste breaking mid-Phase-2 from a Multiattack hit inflicts Lethargic (lose a full action on next turn), and losing a turn while surrounded by lightning markers is frequently lethal.

Spell alternatives to pillars:

• Globe of Invulnerability (Level 6 Wizard/Bard): Creates a fixed zone that blocks all damage for characters inside. Reliable for groups but consumes a high-level slot.
• Otiluke’s Resilient Sphere (Level 4 Wizard): Encases one character in a damage-immune bubble for the duration. They can’t act while inside, but they survive with certainty [1].

After Nova resolves, combat enters Phase 2. The arena floor now has persistent lightning activity, and Ansur no longer exclusively uses flight-based breath attacks. The fight’s rhythm changes completely.

Phase 2: Reading the Bout of Storms Lightning Pools

After Stormheart Nova, Ansur begins using Bout of Storms every round — placing five lightning strike zones across the arena. The mechanic that competitors miss: the five zone markers appear as blue circles at the start of the round, but the actual lightning damage doesn’t land until the end of that round [2]. You have a full turn of actions, bonus actions, and movement to exit any zone before it fires.

Zone placement is randomized each round with no fixed pattern [2]. No location is permanently safe between rounds — a clear corner in Round 3 may have three overlapping zones in Round 4. Check the arena at the start of each turn before spending actions. Step out of any active zone, then use your actions from the new position rather than in place.

The Ansur’s Ire condition icon is your real-time positioning read. If the icon is active on a character, they are inside a current lightning zone and will take damage at round end. The icon disappears when they step outside. If two zones overlap in one area, the icon remains until the character has fully exited all coverage [6]. Watch for this when multiple zones cluster in one quadrant.

Each strike deals 6d10 lightning damage (6–60 per strike) [2]. Being caught in a single strike is survivable with Elixir of Lightning Resistance active; being caught in two overlapping zones is a 12–120 damage hit that drops most builds before Ansur’s own attacks. Spread the party across different quadrants of the arena — if everyone clusters in the same “clear” area by instinct, one bad round of zone placement catches all four.

Movement tools matter more in Phase 2 than Phase 1:

• Misty Step (bonus action, 18m teleport): Moves a character out of any zone without consuming main action movement. The best repositioning option available.
• Dimension Door (action): More range, two-person teleport, but uses the main action.
• Dash (action or Cunning Action for Rogues): Doubles movement for the turn. Reserve for situations where normal movement doesn’t reach clear ground.

Ansur continues Multiattack and Lightning Breath alongside Bout of Storms in Phase 2. Don’t stand still after hitting him — Draconic Wrath retaliation still applies to the first damaging hit per round. Move to clear a zone, attack, move again if needed before round end.

Party Composition by Player Type

Three party frameworks built around the fight’s core demands. Choose the one matching your difficulty and build investment:

The Potions of Speed vs Haste distinction matters most on Tactician and Honour Mode. Haste requires Concentration — one Multiattack connecting with your Concentration holder breaks the spell, removes the bonus action and movement granted, and inflicts Lethargic on every Hasted character. Potions of Speed grant identical action economy without any Concentration dependency and can be used in Phase 2 without the Lethargic risk [5].

If you don’t have a Way of the Open Hand Monk, the next-best Draconic Wrath mitigation is positioning. Keep your opening attacker at the edge of melee range, away from the rest of the party, so the retaliatory Lightning Breath hits one character rather than clustering damage.

Honour Mode: Ansur Gets a Second Life

Honour Mode changes Ansur in ways that invalidate several standard strategies. The most important addition is Unrelenting Storm: when Ansur reaches 0 HP for the first time, he doesn’t die. He stays at 1 HP, gains 100 temporary hit points, and immediately uses Stormheart Nova again [8]. The fight continues with a second Nova requiring a second escape.

The practical implication: any single-use Nova counter is now only good for one of two events. Globe of Invulnerability (if used for Nova 1) may be on cooldown when Nova 2 fires. Plan pillar dashes as the primary Nova counter for both events, and keep Globe as the backup for whichever one goes wrong. Don’t treat Globe as the primary — it only covers one.

Legendary Resistance (3 uses per round, +10 bonus to the next saving throw each use) makes any strategy relying on high-DC spells significantly less reliable [3]. Against Ansur’s CON +6 saving throw and Advantage from Magic Resistance, a standard DC 18 Stunning Strike attempt already faces ~56% failure. Legendary Resistance converts another three potential failures into passes per round. CC-focused builds that built around Hold Monster or Banishment need a backup plan; builds that deal damage without save DCs (physical attacks, Wall of Fire, Hunter’s Mark) are unaffected.

At 600 HP with −4 damage per hit from Greater Wyrm’s Scales, the fight runs 40–50% longer than Balanced. Wall of Fire is worth highlighting here specifically: it deals fire damage (unresisted, no save, consistent) on Ansur’s own turns as he repositions or flies, giving spellcasters passive damage ticks without spending further actions [1]. Cast it in Phase 1 and let it work through both Nova phases.

Honour Mode target order:

1. Push any Myrmidon near the edge immediately with Repelling Blast or Thunderwave (free elimination).
2. Burn all burst tools on Ansur in Phase 1 — Arrows of Dragon-Slaying, Divine Smite, action surges.
3. Pillar dash for Nova 1. Wall of Fire already ticking.
4. Phase 2: spread party, clear zones, maintain pressure.
5. When Ansur hits 0 HP: pillar dash immediately for Nova 2 (100 temp HP at 1 HP base = 101 effective HP). Don’t celebrate. The second Nova kills parties who relax.
6. After Nova 2: finish the 101 HP with two rounds of attacks. Fight ends.

Loot

Ansur drops Balduran’s Giantslayer, a very rare two-handed greatsword. Its Giantslayer enchantment doubles the wielder’s STR modifier on damage rolls against creatures larger than themselves — relevant for Act 3’s finale encounters, not for the Ansur fight itself since you just killed the qualifying target.

The Helm of Balduran sits on the altar behind Ansur’s corpse. Pick it up before interacting with Ansur — once combat begins, the altar is unreachable. The helmet grants +1 AC, +1 to all saving throws, 10 HP regeneration per turn at the start of the wearer’s turn, and immunity to Stunning Strike and critical hits. The crit immunity alone makes it competitive with almost any Act 3 helmet alternative.

Defeating Ansur completes Tales of Ansur in Wyll’s questline and unlocks his Act 3 companion conclusion. For Wyll’s full romance and quest resolution, see our BG3 Beginner’s Guide for companion overview and unlock conditions. If you’re also preparing for the finale, the BG3 Honour Mode tips guide covers the three most run-ending deaths in the final stretch.

Frequently Asked Questions

Can Ansur be stunned to cancel Stormheart Nova?

Yes, and it’s the most impactful single action available in the fight. Stunned during Gather Power cancels the flight animation and skips Stormheart Nova entirely. Way of the Open Hand’s Stunning Strike (CON save) is the reliable source. At Ansur’s CON +6 with Magic Resistance granting Advantage on the save, forcing it through requires a high Monk proficiency bonus and good Ki management. If the stun lands on Honour Mode, Legendary Resistance can convert a failed save to a pass — but using a Legendary Resistance charge on a CON save still costs Ansur a resource. Worth attempting on Honour Mode even with lower odds.

Does cold damage work on Ansur?

Yes. Ansur is immune to lightning but takes normal damage from cold, fire, radiant, and physical types. Cold has a secondary benefit: the Water Myrmidons that assist Ansur are vulnerable to cold damage, giving cold spellcasters a rare multi-target window in Phase 1. Ray of Frost, Cone of Cold, and Snowburst Ring all contribute fully.

Do I need Wyll in my party to access or complete the Ansur fight?

No. The Wyrmway and Ansur are accessible with any party composition, and killing Ansur resolves Wyll’s quest update regardless of whether Wyll is in your active party. However, Wyll needs to be your active companion at some point during Act 3 to receive the full questline dialogue and conclusion. If Wyll is in camp, he still receives the quest completion when you return.

What’s the fastest way to handle the Honour Mode double Nova?

Treat the fight as two phases with a mandatory interrupt between them. For Nova 1: deal maximum burst in Phase 1, then pillar dash with everyone before Gather Power completes. For Nova 2: the moment Ansur hits 0 HP, dash for cover again — don’t spend any actions, don’t attack, just move. Ansur has 100 temporary HP at 1 HP base (101 effective HP to burn through). After Nova 2 resolves, two rounds of focused burst finishes the fight. See our BG3 Honour Mode guide for broader run preparation that covers the other three run-ending boss encounters.

Sources

• Fighting Ansur — bg3.wiki
• Bout of Storms — bg3.wiki
• Legendary Actions — bg3.wiki
• Ansur — bg3.wiki
• Baldur’s Gate 3: Ansur Boss Guide — Game Rant
• How To Beat Ansur — TheGamer
• Ansur (Boss) — Fextralife
• BG3 Honour Mode Boss Fight Changes — TheGamer
• Wyrmway Guide and How to Beat Ansur — Keen Gamer

Michael R.

I've been playing video games for over 20 years, spanning everything from early PC titles to modern open-world games. I started Switchblade Gaming to publish the kind of accurate, well-researched guides I always wanted to find — built on primary sources, tested in-game, and kept up to date after patches. I currently focus on Minecraft and Pokémon GO.