The Eternal Stockade

The Eternal Stockade is a prison located in the astral plane.

Description
The Eternal Stockade sits atop an island in a giant lake comprised of swirling rainbow-hued waters. The prison itself is a massive fortress made of stone and steel.

Souls who conspire to escape the astral plane are imprisoned here and any that successfully escape are hunted down by the Raven Queen's bounty hunter, Kravitz.

The Crystal Kingdom
At some point, Maureen Miller was imprisoned in the Eternal Stockade for conspiring to leave the astral plane and return to the material plane. The events of The Crystal Kingdom are kicked off by her escaping The Eternal Stockade, with her son, Lucas', help and they are both branded as criminals to be hunted down and brought to the Stockade.