The Antagonist will have learned from their confrontation with the MC, and because of this, will have at least a little bit of an upper hand. Knowing what the Antagonist values from that interaction will be helpful in generating how their final confrontation goes.
Unless you’re intending to write a tragedy, it’s assumed that your MC is going to succeed in the end. Thus, it means that in some way, your Antagonist must have a downfall.
The Antagonist should in some way reflect the Protagonist, that is, your MC. While, yes, in some instances the protagonist is their own antagonist, this is for the external antagonists out there. However, that’s not to say that the antagonistic qualities of your MC can’t be personified and developed in this spread as well.