Krakoa, the mutant nation that has solved death.
vs.
Ultron, the Avengers AI archenemesis.
To be more specific, this shall be more of a scenario rather than an arena bout.
Ultron will take the form of the robotic hoard which destroyed a country in the Utron Unlimited storyline of the Avengers.
Krakoa will be as it was during the beginning of the current Judgement Day event.
No back up from the rest of the planet Earth will be available for the X-Men, however they can get Back up from Arakko, assuming that the gates don't get destroyed