In this story, the mystic entity Charnal has all but exterminated most of the life on Earth-9939. In his final battles against the superheroes of this world, Spider-Man, Daredevil, Doctor Strange and the Punisher all die in their final confrontation with Charnal. Charnal has components which can be traced back to an earlier version of Death's Head and the Avengers go back in time to 1992 to see if they can defeat him there.
However, I can find no trace of the X-men in this particular comic and no mention of Professor X or Colossus. I believe there are other Death's Head and X-men crossovers and I will look through them when I get a moment.
UPDATE: Having had a moment, I found a issues of Death's Head Vol. 2 and in 1992 (lasting up to issue #16), the X-men do appear in this second volume of Death's Head. These two volumes are likely the series you are looking for when you are seeking a major crossover between the Death Head and Marvel characters.
The enemy are adaptable mechanized-organisms called Raptors whose abilities include power-adaption. The more you used your powers against them, the better they fought. Their abilities included self-repair making them formidable foes, getting better the longer you fought them.