Baldur's Gate 3 Companion Builds: Classes, Subclasses, and Party Synergy

What You Will Be Able to Do After This Guide

You will be able to look at any companion and name the role they fill, spot a hole in the party, and identify the level or feat that would fix it; you will be able to work out whether a damage feat is actually an upgrade against the enemies in front of you rather than assuming it is; and you will be able to respec a companion at Withers with a plan instead of a guess.

The wrong mental model is that companions are their starting classes. Every companion can be fully respecced — class, subclass, ability scores, feats — for a modest gold fee at Withers, repeatedly. The default class is a starting suggestion and nothing more. What you cannot easily change is the party's composition of roles, and that is what you should actually be planning.

The second wrong model is that bigger damage dice make a better character. In D&D 5e, and therefore in Baldur's Gate 3, damage is the last thing you optimise. What decides a fight is the action economy — how many meaningful things your party does per round versus the enemy — and the reliability of those things, governed by attack bonuses, spell save DCs, and concentration. A party that removes two enemies from the fight for three rounds beats a party dealing more raw damage to all of them, because enemies that cannot act deal none.

The Numbers That Govern Every Build

Action economy. Each character gets one action, one bonus action, one reaction, and movement per round. Builds are differentiated almost entirely by what they do with the bonus action and the reaction, because the action is contested by everyone. A Rogue with Cunning Action has a guaranteed bonus action every round; a Great Weapon Master Fighter gets one only on a crit or a kill; a character with no bonus action option at all is leaving a third of its turn unused. When you evaluate a build, count its bonus action usage — that is often worth more than its damage-per-round number suggests.

Attack math. An attack roll is d20 plus proficiency bonus plus ability modifier plus weapon enchantment, against armour class. Proficiency is +2 at levels 1 to 4, +3 at 5 to 8, and +4 at 9 to 12, so a level 12 fighter with 20 Strength and a +1 weapon attacks at +10 before situational modifiers.

Spell save DC. The formula is 8 plus proficiency bonus plus your spellcasting modifier: 8 + 4 + 5 = 17 at level 12 with a 20 in the casting stat, before items, and 8 + 3 + 4 = 15 at level 5 with an 18. Control spells are all-or-nothing, so a +1 to DC is worth more than it looks, and a caster who neglected their casting stat whiffs.

The Great Weapon Master equation. The feat trades five points of accuracy for ten points of damage. It is an upgrade when (p - 0.25) x (D + 10) exceeds p x D, where p is your chance to hit and D is your average damage per hit. Solving for the break-even: it is worth it when p is greater than roughly 0.25 + 0.025 x D. With a greatsword averaging seven plus your Strength modifier — say twelve — you need better than about a fifty-five percent hit chance for the trade to pay. Against a heavily armoured boss you only hit on a fifteen or better, it is a strict downgrade. Toggle it on for soft targets and off for hard ones; the feat is not a permanent switch. Advantage moves the threshold substantially in your favour, because advantage is worth roughly a plus-three to plus-five bonus depending on the target number, which is why Reckless Attack, Bless, and attacking from stealth change the calculus rather than just adding flavour.

Concentration. Your best spells — Bless, Haste, Spirit Guardians, Hold Person, Hunger of Hadar — require concentration, and you can only concentrate on one at a time. Taking damage forces a Constitution saving throw to maintain it, with a DC of ten or half the damage taken, whichever is higher. This is why concentration protection is a build-defining concern: War Caster gives advantage on those saves, Resilient (Constitution) gives proficiency in them, and a high Constitution score helps directly. A caster who loses concentration every round is a caster who is wasting spell slots.

Rest economy. Long rests consume camp supplies, so you cannot rest after every fight, and short rests are what make short-rest classes strong. Warlock slots, Battle Master superiority dice, Action Surge, Channel Divinity, and Bardic Inspiration (once a Bard reaches the level where it refreshes on a short rest) all return on a short rest, while leveled spell slots mostly do not. A party built on short-rest resources pushes far deeper between rests than one built purely on spell slots.

Level 12 cap and ASIs. The campaign caps at level 12, with ASIs at 4, 8, and 12 for most classes, plus an extra at 6 for Fighters and 10 for Rogues. Most characters get three ASIs and a Fighter gets four, which is why Fighters can afford a maxed stat and two feats while everyone else chooses between them.

Breakpoints that matter. The table below is the short version of what each class gets at the levels where a multiclass decision usually happens.

A full caster at level 12 has four first-level slots, three each of second through fourth, two fifth-level, and one sixth-level. A Warlock at 12 has three slots, all fifth level, recovering on a short rest: fewer casts per fight, far more per day.

Note that Baldur's Gate 3 deviates from tabletop in a few places — Extra Attack interactions when multiclassing martials, some dual-wielding permissions, and Tavern Brawler all differ from the paper rules. Verify any interaction before you commit a split around it.

Build One: Lae'zel as a Battle Master Anchor

Role. Front-line damage that also controls the battlefield, and the most reliable reaction user in the party.

Plan. Pure Battle Master Fighter to 12. Start 17 Strength, 14 Constitution, 10 Dexterity; take Great Weapon Fighting or Defense as the fighting style. Level 3: Battle Master, picking maneuvers that trigger off your reaction or that disrupt enemy actions — Riposte for a reaction attack when an enemy misses you, plus one disarming or tripping option and Precision Attack to rescue a badly rolled Great Weapon Master swing. Level 4: Great Weapon Master. Level 5: Extra Attack. Level 6: the Fighter's bonus ASI into Strength to reach 20. Level 8: Resilient or Tough depending on whether you find yourself failing saving throws or simply running out of health. Level 12: Savage Attacker or a defensive feat.

Why pure rather than multiclassed. Battle Master scales directly with Fighter level: maneuver dice grow, you get a third attack at 11, and you collect four ASIs. Any dip costs you the third attack, and nothing in the game returns more than that plus the level 12 ASI.

Play pattern. Open with Action Surge on round one against the highest-value target. Use Precision Attack when a Great Weapon Master swing is about to miss, which turns the accuracy penalty into a choice. Hold Riposte for the melee attacker that just missed you, so your reaction is never wasted.

Build Two: Astarion as the Gloom Stalker Assassin

Role. Initiative, precision burst, and the party's skill and scouting layer.

Plan. Ranger 5, then Rogue 3, then Fighter 4; or Ranger 5 / Rogue 4 / Fighter 3 if you prefer the extra ASI and more Sneak Attack dice over Action Surge. Start 17 Dexterity, 16 Wisdom, 14 Constitution. Ranger 2 gives the Archery fighting style, a flat +2 to ranged attacks and the strongest accuracy boost available here, which shifts the Sharpshooter break-even in your favour. Ranger 3: Gloom Stalker, for the extra first-turn attack and an initiative bonus. Ranger 4: Sharpshooter. Ranger 5: Extra Attack. Then Rogue for Cunning Action, Sneak Attack dice, and Assassin, which grants advantage against enemies that have not acted and automatic criticals against surprised ones. Finish on Fighter for Action Surge, or on Rogue for more Sneak Attack.

Why this order. The thesis is winning the first round: high initiative means you act before enemies have acted, so Assassin's advantage condition is live and your crits are planned rather than lucky. The order is fixed by the math — Extra Attack at 5 and Sharpshooter at 4 are both payoffs you cannot delay.

Play pattern. Attack from stealth or from outside line of sight so the opening volley has advantage. Spend the bonus action every round — hide, dash, or off-hand attack — because a Rogue with an unused bonus action is wasting the class. Save Action Surge for a second full volley on the turn you have advantage, not for chip damage later.

Build Three: Shadowheart Respected Into a Spirit Guardians Engine

Role. Zone control, sustained area damage, and the party's healing safety net — in that order.

Plan. Respec out of Trickery Domain into Life or Light Domain and take Cleric to 12, or Cleric 11 with a one-level dip if you want a specific armour or cantrip package. Prioritise Wisdom to 20, then Constitution, then a modest Dexterity for initiative. Level 4: War Caster, because your entire contribution depends on maintaining concentration on Spirit Guardians while standing in melee range. Level 8: Resilient (Constitution) or an Wisdom increase depending on whether you are losing concentration or landing fewer spells than you would like. Level 12: the remaining ASI.

Why Spirit Guardians is the build. It damages every enemy that starts its turn or moves within its radius, scales with your spell slots, and needs no attack roll — enemies still take half damage on a successful save. That means reliable work every round from a single action, the best action-per-value ratio a Cleric has. Once it is running, your action is free each round for a cantrip, a heal, or control.

Play pattern. Cast it before contact, walk into the middle of the enemy group, then spend your free actions on healing or control. Do not delay the zone by a round to cast a burst spell; five rounds of the zone outweigh one burst.

Build Four: Wyll as the Lockadin and Karlach as the Thrower. Two more builds worth knowing, because they solve problems the first three do not.

Wyll — Paladin 7 / Warlock 5. Take Paladin to 2 for Divine Smite, 5 for Extra Attack, and 6 for Aura of Protection, then add Warlock for Pact of the Blade. Pact of the Blade lets weapon attacks use Charisma, collapsing the Paladin's usual two-stat dependency into one, and it supplies short-rest slots you convert into smites. Aura of Protection adds your Charisma bonus to nearby allies' saving throws, one of the strongest defensive effects in the game and invisible on a damage spreadsheet. Max Charisma, then Constitution. Divine Smite scales from 2d8 at a first-level slot to a 5d8 cap, plus an extra d8 against undead and fiends, so slots that return every fight beat one big slot per day.

Karlach — Berserker Barbarian 5 / Thief Rogue 3 / Fighter 4. The interaction that makes this build is Fast Hands at Rogue 3, which grants a second bonus action. A Berserker's Frenzy already lets you attack with a bonus action while raging; a second bonus action means a second throw in the same round. Add Tavern Brawler, which in Baldur's Gate 3 adds your Strength modifier twice to unarmed and thrown damage, and you get heavy ranged damage on a Barbarian's health pool and damage resistance. Take Strength to 20, Tavern Brawler at the first ASI, and Fighter levels for Action Surge; confirm the Frenzy downside in game, since the game relaxes some tabletop penalties.

Advanced Applications

Concentration protection as a party plan. Decide in advance who concentrates on what, and make sure that character has War Caster or Resilient (Constitution). If two characters both want to concentrate, one is wasted — move the second onto non-concentration damage or healing.

Stacking initiative. Acting first is the strongest force multiplier available, because a round in which the enemy never acts is a round in which you take no damage. Alert gives a flat +5 to initiative and prevents surprise, which is why it competes with damage feats on controllers. Combine it with class bonuses and high Dexterity and you can reliably act before entire enemy groups, turning control spells from reactive into preventive.

The Wet condition. Creating water on a group and then hitting them with lightning or cold roughly doubles that damage in Baldur's Gate 3. One action spent making enemies wet is often the highest-damage action available to a caster that round, which is why a support character can be the party's damage enabler.

Darkness and Devil's Sight. A Warlock with Devil's Sight sees through magical darkness while enemies inside cannot see out. Casting Darkness on a group and standing in it gives you advantage on attacks and imposes disadvantage on attacks against you: offence and defence from one action.

Smite economy. Do not smite on every hit. The correct question is whether this hit ends a threat or triggers a crit. Smiting on a critical doubles the smite dice, the highest-value use of a slot in the game; smiting a nearly dead enemy with a fourth-level slot is waste.

Respec as a tool. Withers respecs for gold, repeatedly. If a fight goes badly, the fastest fix is often a different distribution: move an ASI into your controller's casting stat, or swap a feat that underperforms against the armour classes you face.

Common Mistakes and Their Fixes

Spreading ability scores across four stats. Every class has one stat that governs its attack rolls or its spell save DC, and that stat should reach 20. Fix: 16 in the primary, 14 in Constitution, 14 in a secondary, dump the rest, and use ASIs to reach 20 by level 8.

Taking a damage feat before maxing the primary stat. A feat that adds ten damage is worth less than the accuracy and DC you lose by sitting at 16 instead of 20. Fix: primary stat to 20 first, feats after.

Two characters concentrating on two spells and both losing them. Concentration is one per caster, and overlapping control is redundant. Fix: assign one controller and have everyone else do damage or support.

Leaving bonus actions unused. A character with no bonus action option is losing a third of its turn. Fix: give every character either a class feature, an off-hand weapon, or a spell that uses the bonus action.

Judging a build by its biggest number rather than its reliability. A 6d6 Sneak Attack that lands once a fight is worse than two reliable attacks. Fix: compute hit chance and DC before comparing dice.

Never respeccing companions. The default classes are starting points. Fix: respec once you know what role each companion should fill.

Long resting after every fight. Camp supplies are finite. Fix: build in short-rest resources — Warlock slots, superiority dice, Bardic Inspiration — so you can push deeper between rests.

A Practice Plan With Self-Diagnosis

Step one, audit by role, not by class. For each character, write down what they do with their action, bonus action, and reaction on a typical round. Anyone who cannot answer one of the three has a hole, and the fix is a level, a feat, or a respec — not more damage.

Step two, audit reliability. Note each character's attack bonus and spell save DC. A level 9 character with a DC below 15 or an attack bonus below +8 is under-built, and the cause is almost always a primary stat that never reached 20.

Step three, audit the first round. Play two fights whose only goal is acting first and removing the two most dangerous enemies in round one. If you cannot, your problem is initiative or control, not damage.

Step four, audit resource depth. Count how many fights you can handle before a long rest. Fewer than three means you are over-reliant on leveled slots and should add a short-rest class or a martial character.

Self-diagnosis after a lost fight, in order: did anyone lose concentration, and did they have War Caster or Resilient? Did anyone end a round with an unused bonus action? Did the party act before the enemy at all? Did you spend a high-level slot on a target that was already dying? Each has a specific fix, and none of them is "get better gear."

Closing Synthesis

Baldur's Gate 3 rewards parties, not characters. Three things decide fights: how many meaningful actions your side takes per round, how reliable those actions are, and how long you can sustain them — and every decision in this guide, from maxing a primary stat before taking a feat to giving every companion a bonus action, is downstream of those three. Build one character who controls, one who bursts, one who sustains, and one who holds the line; make sure the controller can keep concentration; and use Withers freely, because the cost of a wrong build is a little gold, while the cost of never experimenting is a party that is subtly wrong for the whole campaign.