The Sixth Sathlattae
The Sixth Sathlattae is a fictional incantation which first appeared Brian Lumley's The Caller of the Black. It features heavily in another of his short stories namely The Horror at Oakdeene.
The Sixth Sathlattae is a short incantation used to invoke the powers of Yibb-Tstll. It serves as the corner stone for several powerful pieces of magic. What follows is the closest phonetic representation.
Ghe'phnglui, mglw'ngh ghee-yh, Yibb-Tstll,
Fhtagn mglw y'tlette ngh'wgah, Yibb-Tstll,
Ghe'phnglui mglw-ngh ahkobhg'shg, Yibb-Tstll;
Thabaithe -- Yibb-Tstll, Yibb-Tstll, Yibb-Tstll
If the Sixth Sathlattae is repeated once before the caster falls asleep it may allow them to travel to the Jungles of Kled in the Dreamlands where Yibb-Tstll itself dwells. This effect is by no means certain and the use of certain drugs may also be required.
It is possible to use the powers of the Sixth Sathlattae to call Yibb-Tstll into this world in its physical form. In order to do so a gathering of thirteen must invoke the Sathlattae on the first night of the year. At least seven of the casters must be adepts (having cast the spell at least once before, whether it be to summon or contact Yibb-Tstll). A word of warning must be issued here, for summoning the god in no way guarantees its good temper or its willingness to assist its callers. The Barrier of Naath-Tith is often used to protect the casters from Yibb-Tstll possible displeasure.
Calling the Black
The Sixth Sathlattae can also be used to forge a link between a person and the black blood of Yibb-Tstll. In order to do so the caster must inscribe the Sixth Sathlattae in its original Ptetholite glyphs upon a wafer. This must be given to the intended victim (they need not eat it, only touch it). Reciting the Hoy-Dhin Chant within hearing distance of such a person will cause them to be attacked by The Black. This sticky black substance rather like tarry snow will start to materialise as if from nowhere and adhere to the victim. In the space of a few minutes they will begin to suffocate.
A copy of the Sixth Sathlattae can be found within the pages of the Cthäat Aquadingen. The Ptetholite people were also known to have used the Sixth Sathlattae on occasion and may have left records of it carved into the Broken Columns of Geph. Whether these records have survived up until the present day remain to be seen.