Potion of blood (dNetHack)
|Will not be used by monsters.
Potions of blood makes up 1.8% of all random potions in the dungeon.
All vampires have a 2⁄3 chance of generating with at least one potion of blood - they may carry anywhere from one to four potions, with an equal chance of each quantity.
Quaffing a potion of blood acts similarly to opening a tin to eat, as noted above - you are told what monster's blood it smells like if you are a vampire or any non-herbivorous race, and then given a yes/no prompt for drinking it.