Golem's Pith

"Golems are usually described as unthinking constructs and have effectively become synonymous with insentience. Yet only the most powerful mages know how much effort is required to cast a spell on a golem's stone heart, to force the creature to follow even the simplest commands. Renegade mages somehow learned to draw on the complex magic contained in a golem's obsidian heart to produce a powerful mutagenic potion that affects witchers' brains."

When imbibed, Golem's Pith, a mutagenic potion, provides access to a special enhancement of the Intelligence attribute; this upgrade augments the intensity of a witcher's Signs, but only during moonrise.