Black could have had checkmate here, if not for the fact he was in check himself... I thought here Kd5, d2Nb3 and we could draw by repetition

?? Black must have had one eye on checkmate, and so perhaps didn't see...

that Na2 wins the b4 pawn (which should have been on b3)

? I hadn't put much thought into this, as I figured this was the natural move, but Nd7 was much stronger according to Fritz, and White shouldn't worry about a passing c-pawn

But at least now we have ourselves a proper endgame, with White a pawn up and Black left with a bad bishop

? Wrong way... White has to use King and Knight to somehow force Black's King away from protecting g6

But due to the limited usefulness of Black's Bishop, White will be able to induce a series of zugzwangs... try counting them

? If Ke6, then Nb4 is the only move that prevents a draw (Black's King taking f4) But this hinders White's attack

? Black however makes it easier

By now, any way that Black could defend is hopeless, as there are too many zugzwangs