Chaosium's Call of Cthulhu. Been getting some ideas around this genre and as a lurking fan of Delta Green, there may be more coming...
This appears as a simple chalice of fired grey clay, sometimes inscribed with glyphs dedicating the chalice to the bounty of an aspect of Shub-Niggurath. When used as part of any spell invoking Shub-Niggurath, the caster regains 1 Magic Point expended. More powerful versions of this simple item exist, with powers and risks defined by the Keeper and the chalice exists in many forms, from a simple spiral clay cup found in the back of a 1960s occultist bookshop to exquisite examples of barro negro chalices made outside Oaxaca in Mexico.
Feast of the Black Goat (Cost 1 Magic Point/1 SAN per SIZ point of matter affected.)
This dreadful incantation was discovered by cultists of Shub-Niggurath during an outbreak of the Black Death in Bohemia during 1380 and allowed the cultists to survive through ruinous winter famines. The spell allows the caster to eat 1 SIZ of organic matter (dead or living) and treat it as nutritious food regardless of composition or condition. This spell allows someone to eat rotting compost, poisonous fungi, even living flesh without adverse effect. Inorganic poisons (e.g. arsenic, mercury) still affect the caster normally. Additional SAN may be lost according to what is being eaten or how it was prepared at the Keeper's discretion.