There's only one substance more powerful than adamantium in Marvel comics: popularity-induced plot armour.

He didn't even die there, if you can believe it. Though he is catatonic and carried home by Jean Grey. This is one of the few comic books I actually had.

Immediately after this, Xavier gets pissed and completely mind-wipes Erik, something he promised he'd never do. This causes a part of his psyche to splinter off, eventually kidnap Franklin Richards, and merge with him to become Onslaught.

Then an amnesiac, de-aged Magneto shows up to help the X-Men fight Onslaught.

Comics are wild, man.

The adimantium was actually poisoning him, and his healing factor was fighting it the whole time. So when he lost the metal he became ultra powerful and developed bone claws

He survived having molten adamantium injected onto his bones. I'd guess that this wouldn't be as bad as that was.

Fortunately for him, his adamantium skeleton is unrelated to his healing factor.

Logan burned out his healing factor to survive that (he was fine in the end, though), Xavier retaliated by wiping Magneto's mind but in doing so he created Onslaught, a sentient psionic entity created from the darker parts of their consciousness (Xavier and Magneto's)

I've read comics where wolverine has been dismembered in half and still lives through it.

As others mentioned, he definitely survived. But to add onto that, Deadpool got his healing factor from wolverine, and Deadpool's whole shtick is that he's virtually unkillable.

In order to kill either one of them, you have to kill every single one of their cells. For Deadpool at a certain point, even that won't work, because that happened. He died, then fell in love with the personification of death. That pissed off someone real powerful who then cursed Deadpool with immortality so he can never see his beloved again.

Controlling magnetic fields he couldn't physically move non ferrous metals, but he could sure cause a lot of energy to be dumped in due to induction. Essentially cooking wolverine, and then melting his adamantium into a pile instead of being bone/blade shaped

Magnetic fields, which is part of electromagnetism. He can directly influence one of the fundamental forces of the universe. Magneto is definitely one of the strongest mutants.

If he'd learn to do things besides bend and move metal, he'd be able to do almost anything depending on how acutely strong of a field he could make. With how field lines snap in the sun and make for huge discharges of charged particles, I think Magneto would be able to do a lot even without making hugely powerful fields if he'd learn some science.

Imagine adamantium cancer.

...because comics.