Baldur’s Gate 3 contains a number of unique items that you can theme your entire team around, taking advantage of the effects of those items. These items, however, almost always have a crippling downside. In Baldur’s Gate 3, the Resonance Stone can only be found in one location, and that’s definitely the case here.
Baldur’s Gate 3 Resonance Stone Location
After your first confrontation with Ketheric Thorm atop Moonrise Tower, you gain access to the Necrotic Laboratory in the Mindflayer Colony in Act 2. This area contains the Resonance Stone.