It's the irresistible force fights the immovable object. The Earth would blow up before either wins.
Incidentally that paradox is why death battles like this cant exist. Unstoppable or immovable arent a property, theyre defined by context. If one exists the other cannot, by definition. Same way you cant have two omnipotent beings in the same setting.
(omnipotence itself has a whole slew of issues attached to it)