Before time, before the gods, the primordials gathered the materials of chaos and shaped them into masses of solid land only to destry them and begin anew. The lands were alien and wild creations, limitless in imagination, and bound by only the principals of chaos. These lands would eventually be conquered, shaped, and ruled by the gods and become Faerun as you know it.
Far beneath the surface world is a twisted jumble of landscapes, creatures, and ecosystems known as The Underdark. This network of chasms, caverns, and tunnels that snake throughout Toril are remnants of a world that once was – a world of creation, annihilation, and chaos, and the Underdark is ruled by the King that Crawls.
Torog is the King that Crawls. He is the god of torture and imprisonment, and his realm is the Underdark.