The game features a complex Magick system that allows characters to create different spells by combining runes. These spells can attack enemies, dispel illusions, and heal both the body and items.
Eternal Darkness: Sanity's Requiem also introduces a unique concept called Sanity, which is affected by the actions of enemies seen throughout the game. When an enemy is spotted, the character's Sanity meter drops, leading to hallucinations, distorted visuals, and disorientation. The player can restore Sanity by finishing off a dying enemy, using spells or specific items.