A chaotic mish-mash of a level- mostly one big messy boss-fight. Start by zipping over to apocalyptic Asgard.
The way ahead is blocked by rubble, you'll need a cannon to clear it.
The cannon components are split among two objects. The first is the gold statue to the right- use Captain Marvel to break it down.
The next is the Hulk-Handled crate to the left. Tear it apart.
Assemble both parts, then mount the cannon to clear the door.
Enter to trigger a cutscene which ends with the rise of Surtur.
There's a lot going on here- we're going to stick to the mission here, but check out our collectibles guide to this level for everything else- it's pretty much all in this one stage.
Clear out some of the goons and evade the area attacks, then grab the hulk-handled barrel near center stage.
Run all the way to Surtur to with it- you can't throw it very far, and if you miss it's wasted.
It's a good start, but it's not enough- use Marvel to melt the gold equestrian statue stage right.
Assemble the pieces, and have a Thor charge up the assemblage.
This device summons another barrel. Douse Surtur again, then use Cap or Loki to quell the flame in the middle of the field.
Build a catapult with the pieces and fire it. This will shrink Surtur down to size and put him on the field.
He's a teleporter, so you can't run far- just keep hitting him. His basic knockback does no damage, but run for cover when he start charging up with a fire effect. When you take him to half health, he'll return to giant size. Use Loki's quicktime event to stall him a moment.
Reassemble the shattered catapult pieces into a Cap platform, and take aim at the nearest shield bumper, stage right.
This starts a second round against mini-sized Surtur. Tactics are the same- keep punching, but flee the lava blasts.
Take him down to zero to complete the mission.