I heard somewhere that the odds of it happening are super rare, about 1 in 10,000 in tournament setting.
I've brushed up on how to do it a few times, but always seem to forget how to do it after a few yrs(since I'd practice for both methods).
http://en.lichess.org/QnuISG1D/blackThis game, not particulary great (blunders), shows me mating w/ bishop/knight/pawn. When I saw I had bishop/knight I freaked out thinking I was gonna draw if I lost my pawn.
Usually the bishop is better because it is more of a long range weapon. But if you have the knight don't panic. It is best to position your pawns on the opposite color square as the bishop.
I watched chessnetwork's youtube video on it, then practiced it hardcore for a couple of weeks (the board editor here is great for that). Now I don't think it is possible for me to forget how to do it. I can usually do it in 30-45 seconds from any position.
I still practice it a couple of times every few weeks just to stay fresh. I use it in real games every chance I get, such as when I'm waaaay up in material and my opponent won't resign. Just throw away everything but the bishop and knight, and make them feel silly for not resigning :P.
Just a word of advice, if you use the board editor and play the position against the computer here, play the comp at all levels (1-8). It's actually very easy to mate when the comp plays the perfect moves, but when the comp sucks, it becomes much harder until you see how to block the king from escaping.
Bishop + Knight is very different from Bishop + Knight + Pawn. BKP = just promote the pawn, and use the queen for a simple mate any novice can do... Doing so without that pawn though...
Phase 1: Drive the enemy king to the edge of the board so it can not get off the edge.
Phase 2: Push it towards the corner where the bishop can attack that corner.
There are only 2 squares that are lethal for the king in this setup. Need to get it on the long diagonal on the corners where the bishop can attack.
I like the KRBvsK ending when you surprise your opponent by mating on the edge of the board instead of the corner!
err KNB not KRB
I've played it several times at tournaments and team matches (offline), but most players don't encounter it on the board often.
While ChecssNetwork provides a way to administer the checkmate, it's not optimal, and seems to me to be more difficult than the 'W' method, which should be mate in 20 when the enemy king is cornered in the wrong corner.
