After The Many-Angled Ones
had managed to take control of Earth's Mightiest Heroes through a ritual performed by Lord Mar-Vell
, the former heroes hunted Thanos
, the Avatar of Death, to the ends of the Universe.
Eventually he was forced to crash-land his ship, The Sanctuary
, on an unknown world in an unknown sector of space.
With Thanos in their custody, Lord Mar-Vell was able to carry out the ritual without hindrance and destroy Mistress Death
by sacrificing Thanos to The Many-Angled Ones.
With the ritual completed, Lord Mar-Vell was able to construct a link between The Cancerverse
and every reality,
including the oldest, most atrocious and profane Chthonic realities in Creation, that had been conquered by The Many-Angled Ones and their elders, The Old Ones.
By the time everyone else in The Cancerverse realized what was going on, it was already too late to halt the coming of The Many-Angled Ones.
Many of those who resisted, including the High Abstracts and other cosmic entities, were destroyed while those who were too weak to fight were converted into slaves. In the time since, the now-decaying Sanctuary and the organic, tentacled structures around it have become caked in Limbo Ice.
Because of this, the organic structures are now trapped in a state between life and death and will never be granted access to The Many-Angled One's "blessing" of eternal, corrupt life.
The ruins have become infested with non-violent tentacled creatures that spend much of their time roaming about aimlessly, ignoring anything else that comes near them.
The ruins are also watched over by ancient and abominable intelligences who exist beyond the measures of normal cosmic dimensions and whose telepathic presence can cause lesser telepaths to become sick from continued exposure to their otherness.