Netherworld

[Becky]

The Netherworld is Marvel Comics attempt at the definement of Hell, complete with its own ruler [Mephisto]. Same fire, brimstone, little demons, screaming souls, etc. Whenever an evil character dies, he always ends up there. The Netherworld can be breached by only the most powerful of sorcerers (such as [Dr Strange]) and the lost souls can be rescued on occasion.
Currently the Netherworld is ruled by the Demoinic entity known as [Blackheart], who after killing his father Mephisto, usurped the power of the Netherworld for himself and became the current ruler.

[Lizzy Liz]

a place, situation, or part of society that is hidden and often unpleasant: