|“||... I wanted to bound, to float in my madness through eldritch depths of unhallowed black blood. I wanted to cling to the writhing breasts of Yibb-Tstll. Insane....||„|
|~ Brian Lumley , -Rising with Surtsey|
Yibb-Tstll (The Patient One) is an obscure god, said to watch at the center of all time as the universe revolves. Because of this insight, only Yog-Sothoth is said to be wiser. Its blood, the Black, is a weapon which takes the form of black snowflakes that stick to and smother a victim. The god's touch causes an instant change in the person affected—this change is usually fatal but occasionally brings some benefit.
Yibb-Tstll is sometimes described as an immobile, dark, tentacled entity with a pulpy, alien head, detached eyes, and large bat wings under which countless Nightgaunt suck black milk from its innumerable breasts.
Having a close connection to the Great Old One Bugg-Shash, so should Yibb-Tstll be regarded as a Great Old One - specifically in the Drowners group introduced by Brian Lumley, parasitic alien entities which thrive by vampyrizing the Great Old Ones themselves - though in RPG materials she is classed as "Outer God".