
The Dwell of Souls was originally a dungeon decal sticker that came in the box and kids would apply to one of the floor sections of the toy of Castle Grayskull.
From that sticker was birthed the characters of Frog Monger and the Orlax of Primeria.
Turtles of Grayskull[]

In the Turtles of Grayskull mini comic story, The Spirit of Gray-Shell, The Sorceress sent the Turtles and April O'Neil, with new Sorceress powers, deep into the bowels of Castle Grayskull to the Dwell of Souls to meditate and call upon the Spirit of Grayskull to help them find the Sword of Power.
The Dwell of Souls is depicted as a pool of water, surrounded by dungeon cells, filled with monsters and creatures, like the Orlax of Primeria.