Got my first brilliant move

Can someone explain why promoting to a rook is better here?

Find the only move for white that works

This is why you never resign kids, was playing bullet chess being down 8 points of material and this happened. White to play and mate in 3

My friend forgot about the special move

Can you find mate in 5? (White to play and win)

Props to him for not resigning and being a good sport lol

After forever, I’ve finally hit 1000 blitz for the second time (I dropped to 980 on my first)

This dude made me wait like 5 minutes before the autoresign

It wasn't even a dead lost position, I could have blundered all my pieces in those 5 minutes but he wasted both of our time

How is this opening named? Never seen such before.

Why is it a brilliant?