Larian's games use a custom-built combat system nicknamed "Jane" that controls how enemies think and act during turn-based battles. Jane is not machine learning — it works by running mathematical simulations of every possible action an enemy could take, scoring each one, and picking the highest-scoring option based on the enemy's assigned fighting style.

Jane evaluates every available skill against every valid target in a combat encounter, calculating expected damage, healing value, buff effectiveness, and positional advantage. Each enemy type is assigned an "archetype" (such as Healer, Ranger, or Berserker) that applies score multipliers to favor actions matching that role — a Healer archetype will score healing spells higher and offensive spells lower. The system uses a separate AI Grid to track hazardous surfaces like fire and poison pools. Level designers can place special "AiHint" trigger zones to guide enemy positioning preferences. The game's difficulty is partly managed by intelligence-gating: less intelligent creatures, like imps or beasts, are deliberately prevented from using advanced tactics. Jane was significantly enhanced across Baldur's Gate 3's post-launch patches, with Patch 5 adding the ability for enemies to reason about stamina resources and friendly-fire consequences.