Ok so I think I have a pretty possible prediction of what will happen in this episode. First let's start with the synopsis:
Now, my prediction:
I'm not sure why, but obviously Ice King and FP do battle. I'll make some predictions as to why they would fight after this. While they fight, Finn dreams about the battle and sees Flame Princess succeeding and killing the Ice King, which leads to the crown freezing the earth in mourning. Not wanting this to happen, he awakes and rescues the Ice King, much to FP's confusion. He says that he can't let FP hurt him and, caught up in her tantrum of rage, she continues attacking. Finn is forced to stop her. Not sure what would happen after that. Anyways, the iTunes description of this season says that PB discovers something in the wreckage. I think this will be something involving FP's elemental matrix but it could also be something relating to IK's backstory too or it could just be something completely unrelated.
Now, FP and IK fighting reason predictions:
-IK tries to steal FP.
-FP tries to rescue Finn from IK and Finn has already been knocked out by IK which causes him to dream.
Discuss your predictions.