ahh, my mistake: i was looking at alternatives to 18. Bxb4. Whupsie.
crap, i missed something.
Bd4 loses. Nc5! followed by Bf5! and the mate threats on c2 are too much to ignore.
Bd6 is unequivocally best, going for the draw.
What is your assessment after 12.Bd4, do you still like 12...Nc5!?
right, transpo asked about 12.Bd4, but not as an alternative to 18.Bxb4.
Ok, a quick overview of why 12.Bd4 wins, without variations. Variations maybe later.
12.Bd4 paralyzes Black's B at f8 preventing ...0-0, which because of White pawns at g5 and h4 is not a good idea. All moves by Black in the center to block White's B at d4 destroys Black's alternate castled position in the center because of his small but secure center (pawns at f7,e6,d6). 12.Bd4 simultaneously threatens 13.Nd5 (d5 is the thematic square in the Sicilian Najdorf and as in this game a Sicilian Najdorf/Scheveningen)
I don't agree that Bd4 wins. black has b4 to work with. Bd4 b4 and the knight has either b1, d1, or d5. Nd1 and Nb1 both lose a pawn to e5 Be3 Qxe4. Nd5 might be in keeping with the spirit of the opening, but white better make his attack count. Nd5!? Qb7 Bg2 (or 0-0-0) exd5 exd5+ Kd8 is certainly ugly, but i think black is winning.