Bilberry

Forest Bilberries are small black berries. They must be mixed with pure alcohol and left to stand for fifteen days, at the end of which time they must be drunk. A successful application will give a human the truesight ability for 2d6 days, but a failed application may lead to the death of the person who drinks it, as if they had drunk a potent poison (DC 17 Cons. Save, or take -25 hit points over 1d4 minutes).