Or have Loki/Odin capture Thor and the Hulk, convict them in some Asgardian kangaroo court and force them to fight in the arena to earn their honor back. Keeps everything neatly connected to the MCU that's already been established and you don't have to spend a lot of time introducing a ton of new characters like the Red King, Miek, etc. Furthermore, you don't have to explain the illuminati, of whom Marvel only has the rights to half and have introduced two or Sakaar. Asgard is already established, Loki is already a money villain, and you know that theater would pop when Hulk finally got his mitts on Loki.