May I ask just... what happened in Caliborn's clay animation scene? I couldn't make sense of any of it!

Caliborn’s claymation scene basically told the story of his fight with the kids. During the fight he trapped the Beta kids in his white house-shaped juju and then banished it to the Furthest Ring. After that he fought all the Alpha kids and Gamzee was cut in half. Jake then attacked him with his Hope powers but it wasn’t enough to kill Caliborn. Then Arquius came out of nowhere and got a hold of Caliborn and held him while Dirk used his Heart powers to seal Caliborn’s soul inside Lil Cal. Unfortunately, both Arquius and half of Gamzee were sealed with him as well. This fight most likely takes place further along the current timeline.