Baldur’s Gate 3 Act 3 Walkthrough

Act 3 is the longest act and the climax of Baldur’s Gate 3. The city is split between Wyrm’s Crossing (outer district) and the Lower City (inner walls). This walkthrough keeps you on the path to the Netherbrain while hitting the key companion resolutions.

Getting Into the City

• Cross Wyrm’s Crossing bridge. Resolve the Counsellor’s Fate and the Open Hand Temple murder mystery.
• Reach the Lower City via the drawbridge after dealing with Gortash’s coronation.

Critical Path Order

1. Resolve companion quests (Astarion vs Cazador, Shadowheart’s choice, Gale’s orb, Wyll’s pact, Karlach’s engine). These close in Act 3 and affect the ending.
2. Deal with Gortash at Wyrm’s Rock — ally, steal the Netherstone, or kill.
3. Steal Orin’s Netherstone (Bhaal temple) or let her take a companion.
4. Storm the Brain — enter the Astral Plane via the underwater colony and face the Netherbrain with both Netherstones.

Key Locations

• Lower City Sewers: shortcuts and the Emperor’s old hideout.
• Sorcerous Sundries: best Act 3 staff and the Mirror of Loss.
• Iron Throne: timed rescue mission (save the duke and prisoners).
• House of Hope: raid Raphael for the Orpheus path option.

Final Tips

Act 3 has timed missions (Iron Throne, Cazador) — do them before pushing the main plot. The Mirror of Loss grants a permanent +2 to an ability score; use it on your main carry. Stack Condition Immunity and Freedom of Movement before the final fight — the Netherbrain relies on control effects.