Sacked the bishop
Post your brilliant moves here(it can be great move)

what if they don't take, but play Kb8?
That would be horrible. White queen takes, check, at that point all black can do is Rd8, take, check mate.

Is this really brilliant ?(dont know) but it has an abrupt ending
Yeah you have his queen. Queen must take B5, Knight takes pawn C7, check, king moves, Knight takes Queen B5. If queen doesn't take, you take with Bb5.

Sacked the bishop
After takes bishop. Do Rd1 sacking your rook to make checkmate available with Qb7

why is Rc8 not brilliant😭😭
game link: Oldshus123 vs. Merciless_Boy | Analysis - Chess.com
because instant mate is NOT forced this time
Please don't post double comments.