The delicious form of the assorted ingredients, the 'mush', of cookie dough that is delicious, or the batter for a pie crust, or the batter that would be deep-fried dough before ending up around a corn dog or piece of fish.
This term used when you are going to “fuck someone up” so hard that they cannot sit onself down for many months.
This term can also be used when you will fuck someone hard during sexual intercourse.
Harry said to James: “I’m going to batter you. Then I’ll batter yer mam”