Krakoa officially has its own X-Men mutant Hell, with Sabretooth as its king

gamesradar.com:

February 2's Sabretooth #1 sets up a terrifying (and terrifyingly appropriate) new status quo for the eponymous mutant villain, with writer Victor LaValle, artists Leonard Kirk and Rain Beredo, and letterer Cory Petit leaning directly into Sabretooth's reputation as one of the worst, most vicious mutants in the Marvel Universe.

With Sabretooth having been stuck in exile in Krakoa's equivalent of prison since House of X/Powers of X, Sabretooth #1 (of 5) finally shows what actually happens in 'the Pit,' and explores the unforeseen consequences of Krakoa's brand of mutant justice.

The vicious mutant murderer Sabretooth was the first recipient of Krakoan justice way back in House of X/Powers of X when he was exiled to a void somewhere deep in Krakoa known as 'The Pit,' where he's been held in stasis - as Xavier describes it "aware but unable to act" - for the violation of killing humans.

He's been stuck there ever since, with neither hide nor hair of the mutant berserker seen above ground on Krakoa. At least, not until Sabretooth #1, in which his visage starts appearing in the foliage of Krakoa, much to Black Tom Cassidy's dismay. 

As it turns out, Sabretooth's been trying to escape the Pit through whatever psychic and physical strength he can muster - and it's getting bad enough that Krakoa sends Doug Ramsey's mind into Sabretooth's consciousness to make him a "plea deal" of sorts.

In what Doug Ramsey calls an "act of mercy," he offers Sabretooth a kind of "psychic freedom," in which his mind will be paradise, rather than a prison, with his awareness of his captivity and the resulting anguish therefore soothed. He also promises Sabretooth that he's trying to ensure no one else shares his fate - but that promise will soon be