One of the strangest new items introduced in Elden Ring: Shadow of the Erdtree is Thiollier’s Concoction , a consumable that, by all indication, will kill the Tarnished the moment they drink it. Players first receive this item during Thiollier’s questline in Shadow of the Erdtree. After they’ve met Thiollier the poisoner for the first time near the Pillar Path Cross Site of Grace, then returned to speak with Moore, the latter merchant will ask them to deliver a pot of Black Syrup. Bring that back to Thiollier, and he’ll share some of his concoction by way of thanks.