The Madaras Whistle is a sinister, intricately crafted musical instrument resembling a small, curved bone flute with dark, weathered finishes. Its surface is adorned with faint, blood-red engravings depicting obscure, eldritch symbols, suggesting its connection to forbidden rituals. The whistle emits an eerie, otherworldly sound when blown, capable of summoning monstrous entities from the unseen depths of the game's universe.