Complete the enthusiastic gamer's livestream announcement by selecting the grammatically correct option.

If I can just keep my eyes open until 3:00 AM, I _______ virtual dragons for 48 hours straight!

The correct answer is will have been battling.

The Future Perfect Continuous is required here because the gamer is projecting themselves into the future (3:00 AM) and looking back at the duration of an ongoing, continuous activity (battling dragons for 48 hours).

"Had been battling" is Past Perfect Continuous, which refers to an action completed in the past, while "will be battling" lacks the perfect aspect needed to express a duration leading up to a future moment.