Most build guides treat Karlach’s infernal engine as a passive flavour mechanic — a bit of fire damage when she’s angry, some immunity to charm if you complete her quest. That misses the point. The Infernal Heart is a rationed resource with 19 total activations across your entire playthrough, and the way you time each one changes how many Bonus Actions you have in combat.
Patch 8 (released April 2025) added Path of the Giants — the subclass that finally matches her personality and her mechanics. Combined with a Fighter dip and the right equipment progression, Karlach becomes the highest single-turn damage dealer in the party when you need it most.
This guide covers Giant Barbarian from subclass selection to end-game equipment, with a per-rest Infernal Heart economy table and a 3-turn Honour Mode burst sequence designed to eliminate priority targets before their Legendary Actions fire. For a broader look at where Karlach sits among all companions, see our BG3 Best Companions guide.
Verified against BG3 Patch 8 (April 2025). Values may change with future updates.
Quick Start: 8 Steps Before You Dig Deeper
New to Karlach, or returning after a long break? Here’s what to do before the theory gets complicated.
- Recruit Karlach in Act 1 — Find her at the Risen Road (north of the Blighted Village) before resolving Wyll’s hunt. She leaves permanently if you side with Zariel’s paladins.
- Respec at Withers if needed — If you recruited her mid-game with already-spent levels, use Withers (200 gold) to reset. Keep all levels in Barbarian for now.
- Choose Giant (Path of the Giants) at Level 3 — Not the default Berserker. Giant is the Patch 8 addition that changes her damage ceiling.
- Point your stat boosts into Strength and Constitution — STR is your primary damage stat; CON keeps you alive long enough to use it.
- Take Great Weapon Master at Level 4 — The +10 flat damage modifier outperforms every other Level 4 option in this build.
- Craft Adamantine Scale Mail in Act 1 Grymforge — Best medium armour until Act 3 and it makes Karlach immune to critical hits, which matters a lot in Honour Mode.
- Activate Soul Coins before combat — not during — Using a Soul Coin mid-fight costs the Bonus Action you need for Giant’s Rage or Boot of the Giants. Activate at camp or in a dialogue cutscene before initiative rolls.
- In Act 3, equip Balduran’s Giantslayer and Gauntlets of Hill Giant Strength — These two items together unlock Karlach’s best-in-slot damage window. More on why below.
Subclass Selection: Why Path of the Giants Wins in 2026
Karlach has four Barbarian subclasses available. Giant was added in Patch 8 — and unlike the others, it was designed after the community had two years of experience with her character and playstyle.
What Giant Gets You
Giant’s Rage (Level 3) replaces the standard Rage: Karlach enlarges to Large size (the Enlarge spell effect), doubles her rage damage bonus on thrown weapon attacks, and gains Thaumaturgy for Intimidation advantage. The size increase isn’t cosmetic — it adjusts how enemies position around her and provides a subtle reach advantage on melee attacks.
Boot of the Giants (Level 5) adds a Bonus Action kick that pushes targets based on an Athletics check. In Honour Mode, pushing a melee enemy off a ledge or into a hazard zone removes it from the fight without costing your Action — a Bonus Action that does the work of a full turn.
Elemental Cleaver (Level 6) adds +1d6 elemental damage during Rage (your choice: Acid, Cold, Fire, Lightning, or Thunder) and makes any weapon throwable with auto-return on hit. Lightning pairs well with wet enemies; Fire is Karlach’s thematic choice. The auto-return mechanic means you never lose a weapon by throwing it.
Mighty Impel (Level 10) lets you throw any Medium or smaller creature as a Bonus Action with no Strength requirement and fixed throw distance. In Honour Mode, this is a free kill on any enemy near a ledge or hazard — it doesn’t use your Action, it requires no roll, and the target doesn’t get a saving throw to resist the environmental hazard.
Subclass Decision Tree
| Your Goal | Best Subclass | Why It Works | When NOT to Choose It |
|---|---|---|---|
| Maximum Honour Mode burst damage | Giant | Elemental Cleaver adds damage, Mighty Impel deletes enemies from ledges, Boot of the Giants provides free positioning | If you dislike managing Bonus Action priorities |
| Simplest melee build | Berserker | Frenzied Strike gives an immediate bonus attack during Rage — lowest decision complexity | Frenzied Strain stacks accumulate attack roll penalties in long fights; action economy tightens on Turn 1 |
| Maximum mobility and no opportunity attacks | Wildheart (Eagle) | Dash as Bonus Action, immunity to disadvantage on opportunity attack rolls | Lower damage ceiling compared to Giant in Act 3 endgame |
| Tankiest possible frontliner | Wildheart (Bear) | Resistance to ALL physical and most elemental damage types while raging | No throw utility; sacrifices damage output for durability |
Starting Stats and Feat Progression
Karlach’s companion defaults (STR 17, DEX 13, CON 15) are functional but leave action economy on the table. If you respec at Withers, the optimised allocation is:
| Stat | Default (Companion) | Respec Target | Reasoning |
|---|---|---|---|
| Strength | 17 | 16 | Great Weapon Master bridges the -1 gap; saving 1 point funds a higher CON |
| Dexterity | 13 | 14 | Medium armour AC uses up to +2 DEX modifier — anything above 14 is wasted |
| Constitution | 15 | 16 | Extra HP per level; CON saves are critical for Concentration spells cast on Karlach by allies |
| Intelligence | 8 | 8 | Dump stat |
| Wisdom | 12 | 10 | Feral Instinct at Level 7 (+3 Initiative) covers the initiative gap; dump this |
| Charisma | 10 | 8 | Dump stat for this build; Thaumaturgy from Giant covers Intimidation when needed |
Feat Schedule
- Level 4 — Great Weapon Master: +10 flat damage on every melee attack when you toggle All In. Also grants a free Bonus Action attack on a critical hit or on any kill. Take this first at Level 4, without exception.
- Level 8 — +2 Strength (ASI): Brings Strength to 18 with the respec, or 19 with default stats. Every +1 STR adds +0.5 average damage per attack; at 5 attacks in the nova round, the compounding adds up.
- Level 12 — +2 Strength (ASI): Reaches STR 20 (or 21 with default). Hold off if you plan to equip Gauntlets of Hill Giant Strength in Act 3 — they set your STR to 23 and make every point you invested in natural STR irrelevant.
The late-game STR respec: Once you have the Gauntlets (Act 3), respec Karlach’s base STR to 8 and redistribute those 14 points into Dexterity (for AC) and Constitution (for HP ceiling). The Gauntlets overwrite your STR score completely. Natural STR above 8 is wasted stat points after that point.
The Infernal Heart: How Many Actions You Actually Get Per Rest
Every Karlach guide mentions Soul Coins. None of them do the math on what they actually give you per rest period.
When Karlach consumes a Soul Coin as a Bonus Action, she gains the Infernal Fury condition until her next long rest. While active, her weapon and unarmed attacks deal an additional 1d4 fire damage when she is Raging or when her HP drops below 25%. Critically, the condition persists across every combat encounter until you rest — one Bonus Action spent before the day’s first fight covers all subsequent fights in the same rest period.
Infernal Heart action count per long rest: 1. One Bonus Action to activate it, then it runs for free through every combat until you sleep.
There are exactly 19 Soul Coins in the entire game:
| Act | Coins Available | Primary Locations |
|---|---|---|
| Act 1 | 5 | Dank Crypt, Emerald Grove (Aradin’s chest), The Risen Road (near where you recruit Karlach) |
| Act 2 | 4 | Reithwin Tollhouse, sold by Lann Tarv at Moonrise Towers |
| Act 3 | 10 | Lower City, Peartree House, Raphael’s safe (boss fight required), scattered vendors |
A standard playthrough uses 20–30 long rests. With 19 coins, you will run out before the credits. Treat Soul Coins as a priority-spend resource, not free passive damage.
Timing rule: Always activate Infernal Fury outside of combat — at camp, during dialogue before a fight triggers, or in the brief window before initiative rolls. A coin activated on Turn 1 costs the Bonus Action you need for Giant’s Rage. You gain 1d4 fire damage and lose a Rage — that’s a net damage loss for most fights.
When to spend: Boss encounters, Honour Mode named enemies, and any fight where Turn 1 Rage entry is non-negotiable. Skip coins on optional trash-mob dungeons in Acts 1 and 2 — Act 3’s 10 coins cover every critical fight if you’re selective.
One mechanical note: if Karlach is simultaneously Raging and below 25% HP, Infernal Fury triggers twice per attack for a total of 2d4 fire damage (confirmed behaviour on bg3.wiki’s condition page). It’s a side effect of two independent trigger conditions being met at once — don’t build around it, but know it exists when she’s fighting through a near-death moment.
Karlach’s Rage charges — the other Infernal Heart resource — scale with Barbarian level:
| Barbarian Level | Rage Charges Per Long Rest |
|---|---|
| 1–2 | 2 |
| 3–5 | 3 |
| 6–8 | 4 |
| 9–11 | 5 |
At max level (12 in BG3), you have 5 rages per rest — sufficient for every meaningful combat in an act without rationing.
Who Should Play Which Build
| Player Type | Subclass | Multiclass? | Priority Actions Each Turn | Soul Coin Strategy |
|---|---|---|---|---|
| New player | Berserker | No | Rage → Attack × 2. Nothing else required. | Use whenever you find a good moment — don’t stress the timing |
| Casual | Giant | No | Giant’s Rage → Attack × 2 → Boot of the Giants next turn | Spend before major boss fights. Skip smaller dungeons. |
| Optimiser | Giant | 4 levels Fighter (Battle Master) | Rage → Attack → Action Surge on Turn 2 or 3 for 4 attacks in one action window | Always active. Track the 19-coin budget from Act 1. |
| HM specialist | Giant | 4 Thief Rogue OR 4 Fighter | Turn 1: Rage (BA1) + Boot of Giants (BA2 via Thief Fast Hands) → 2 attacks. Turn 3: Action Surge nova. | Boss fights only. Hoard coins for the Act 3 crisis fights. |
The Thief Rogue dip (4 levels) solves Berserker’s core problem — bonus action competition — for Giant Barbarian too. Fast Hands gives Karlach a second Bonus Action per turn. On Turn 1 she can use Giant’s Rage (BA1) and Boot of the Giants (BA2) simultaneously, something impossible in a pure Barbarian build. The cost is losing 4 Barbarian levels and delaying Extra Attack, which matters most in Acts 1–2.
Honour Mode Burst Rotation: The 3-Turn Kill Sequence
Honour Mode makes character death permanent and gives boss enemies Legendary Actions — extra abilities that fire between your turns. The counter-strategy is eliminating priority targets before their Legendary Action pool resets. Karlach is your best tool for this, because she front-loads more damage in fewer turns than any other companion.
Pre-Combat Setup
- Infernal Fury already active from the Soul Coin spent before initiative
- Haste cast by Gale or another caster if available (+1 extra Action per turn for Karlach)
- Karlach positioned in melee range of the priority target
Turn 1 — Rage Entry
- Giant’s Rage (Bonus Action) — Karlach enlarges, activates physical damage resistance, doubles throw damage bonus
- Attack × 2 (Action + Extra Attack at Level 5) with GWM All In for +10 damage per hit
- If Hasted: 1 additional Attack (Haste Action) — Turn 1 total: 3 attacks
- If GWM triggers (critical hit or kill): the free Bonus Action attack is unavailable on Turn 1 because Giant’s Rage used your BA — this is why the Fighter dip matters more for Turn 1 output
Turn 2 — Positional Control
- Boot of the Giants (Bonus Action) — Push the priority target into a hazard, off an elevation, or away from your squishies
- Attack × 2 (Action) + Haste Attack if still active
- Elemental Cleaver is now adding +1d6 per attack; total damage stack per hit: Weapon dice + STR modifier + GWM +10 + Elemental +1d6 + Infernal Fury +1d4
Turn 3 — The Nova Round (Giant + Fighter Dip)
- Mighty Impel (Bonus Action) — Throw any Medium or smaller enemy into a pit or hazard for a free removal; no Action cost, no STR check
- Attack × 2 (Action)
- Action Surge — Immediately 2 more attacks in the same turn
- With Haste active: 2 (Action) + 2 (Action Surge) + 1 (Haste) = 5 attacks in one turn, each hitting for Weapon + STR 23 (+6 mod) + GWM +10 + Elemental +1d6 + Infernal Fury +1d4
Priority target order in HM: Ranged spellcasters first — they consistently receive the most dangerous Legendary Actions (area spells, charm effects, summons). After them, any melee enemy threatening your party’s squishiest member. Karlach’s Heart Ablaze (second heart upgrade from Dammon) grants charm immunity, which makes her the safest character to leave in range of charm-aura bosses like Raphael and the House of Hope encounters.
For the full Honour Mode companion strategy, our BG3 Beginner’s Guide covers which encounters in Act 1 are the hardest to recover from if you wipe.
Equipment Progression by Act
| Slot | Act 1 | Act 2 | Act 3 (Best in Slot) |
|---|---|---|---|
| Weapon | Greatsword +1 (vendor, early map) | Shar’s Spear of Evening (stealth runs) or Sussur Greatsword (silence on hit) | Balduran’s Giantslayer (+3, doubles STR modifier per hit) |
| Armour | Adamantine Scale Mail (Grymforge forge — 16 AC, immune to crits) | Dark Justiciar Half-Plate (15+2 AC, Advantage on Stealth) | Helldusk Armour (21 AC, heaviest protection) or keep medium armour for Fast Movement |
| Gloves | Gloves of the Growling Underdog (Advantage when surrounded) | Thermoarcanic Gloves (Arcane Synergy damage if using a melee spell-focused setup) | Gauntlets of Hill Giant Strength (STR set to 23 — triggers the full stat respec) |
| Amulet | Amulet of Misty Step (utility) or standard | Standard | Amulet of Greater Health (CON set to 23 — raises HP ceiling by 20–30 HP at Level 12) |
| Cloak | Standard | Standard | Cloak of Displacement (attackers have Disadvantage on attacks against Karlach — halves incoming hit frequency) |
| Rings | Standard | Standard | Ring of Regeneration (+1d4 HP at turn start) + Ring of Flinging (+1d4 on thrown weapon attacks) if using the throw variant |
Why Balduran’s Giantslayer is best in slot: This +3 greatsword doubles your Strength modifier on every damage roll — not once per attack, but as an additional modifier per hit. With Gauntlets of Hill Giant Strength setting STR to 23 (modifier +6), each attack adds +12 to damage instead of the standard +6. Over 5 attacks in the nova round, that’s +30 extra damage before accounting for GWM, Elemental Cleaver, or Infernal Fury. No other Act 3 weapon closes this gap.
Act 1 priority craft: The Adamantine Scale Mail requires two Mithral Ore found in Grymforge and a kill on the Grym boss to unlock the Adamantine Forge. Complete this before leaving Act 1 — the crit immunity it provides is particularly valuable in Honour Mode, where critical hits deal maximum damage and can end fights before they begin. For more on which Act 1 decisions lock you out of content, see our BG3 Oathbreaker Paladin guide, which covers irreversible quest flags that affect the whole party.
Frequently Asked Questions
Can I use this build as my main character instead of a companion?
Yes. Create a custom Zariel Tiefling Barbarian with the same stat allocation and subclass choices. You’ll have full control over the Infernal Heart quest timing and can guarantee both heart upgrades before Act 2. Every build decision above applies identically to a custom character. The only difference is that companion Karlach has story dialogue and approval triggers tied to her character arc — a custom Karlach-style character skips these.
Do I have to complete Karlach’s heart quest to play this build?
Complete it as early as possible. The first upgrade (Heart of Iron) gives Advantage on charm saving throws, and the second upgrade (Heart Ablaze) replaces it with full immunity to charm effects. In Honour Mode, several Act 3 bosses use area-of-effect charm abilities that can flip your entire party against each other. Karlach with Heart Ablaze stays reliable in these fights when everyone else is compromised. Skipping the quest leaves this defensive gap open for the entire run.
Is the Strength elixir strategy better than Gauntlets of Hill Giant Strength?
Yes — but only with Elixirs of Cloud Giant Strength, not Storm Giant. Cloud Giant Elixirs set STR to 27 (modifier +8), which beats the Gauntlets’ 23. If you have consistent access via the vendor near Wyrm’s Crossing in Act 3, the damage maths favour elixirs. For most runs, the Gauntlets are more practical — they never reset on a long rest, cost nothing to maintain, and the STR 23 floor is within a few damage points of the elixir ceiling across a full nova round.
Sources
- Karlach — bg3.wiki
- Barbarian — bg3.wiki
- Giant (Barbarian Subclass) — bg3.wiki
- Soul Coin — bg3.wiki
- Infernal Fury Condition — bg3.wiki
- Fextralife: Karlach Build Guide (Barbarian / Fighter)
- Gamestegy: Karlach Avernus Avenger Build
- TheGamer: Best Builds For Karlach in BG3
- GameRant: Which Patch 8 Subclass Makes the Most Sense for Karlach
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.