Hastalyk

Hastalyk (alternate spellings: Hastalÿk, The Plague, Pazuzu, Angel of Disease, One Who Shuns the Light)

Origin: Chad Bowser for Malleus Monstrorum (English version)

In the Mythos

One of the most insidious and powerful Great Old Ones, Hastalÿk is the embodiment of disease. When great epidemics or even localized outbreaks of a disease occur, Hastalÿk may be to blame. Hastalÿk is not the disease, but instead acts as an amplifier for a native contagion. It turns an outbreak into an epidemic.
— Chad Bowser, "Hastalÿk" (Malleus Monstrorum entry)

An insidious and powerful Great Old One said to be the embodiment of disease.

Keeper Notes

• As of 2018, there do not appear to be an stories or scenarios published about this Great Old One, and most known information about it can be found primarily in Malleus Monstrorum, along with a few expanded details in Terror Australis.

Cult

• There are no organized cults dedicated to Hastalÿk, though lone cultists or disorganized bands of cultists may invoke this entity for specific destructive purposes; Hastalÿk is resistant to control, and is highly dangerous to summon, especially for the summoner.

References

• Malleus Monstrorum (primary reference)
• Terror Australis (includes a section on diseases of Hastalÿk in Australia)
• YSDC Discussion: "Any Hastalyk Scenarios?"
• YSDC Discussion: "Hastalyk Gog-hoor and Kurpannga"