Very hard puzzle from one of my games

Last year I played at the world youth chess championship in Maribor (Slovenia). In the 7th round I was always completely losing until I created some counterplay and had a chance to draw the game in this position:

Could you post what type of tactic is used?

Qa5 looks promising. Right idea or bad idea?

No, if Qa5, then Ra6 and white will promote.

After Qa5 Ra6, black plays Qxd2 and has a perpetual or more. However, I don't know what black does after Qa5 Nf1. Hmmm...maybe Qb4? Qa5 looks quite good! But what about Nb1?

There's no perpetual check…

After Nf1 or b1, I was thinking Qe1 and promote my own pawn. Material should equal out at the end for all the branches I calculated.

I agree with your calculations, falcongrine.  If white should promote, Rxa8 and white plays Qxa8 and gets a check and black plays Kh7, but now the black queen is protecting e4 so white cannot do much better.  If white takes the black bishop (Qxa3) then black promotes and has 2 queens on the 1st row

I looked it up with an engine, and although Qa5 is the best move for black, the position is winning for white. The correct response for white is Rc2, but the position may be drawn if white promotes.

@Maximus I don't know which engine you used, but the position is drawn after Rc2 as well (I let Houdini 3 run till depth 26). You have to find only moves then but it's still a draw. Also, I can't tell you the "type" used, because this is not a two-mover with a double attack and there are too many lines with different ideas.

P.S. Sorry for not answering so long, but in Germany it was 1 A.M. and I had to sleep.

Uhhh... I used chess.com's iOs engine. [awkward embarrased laugh]

P.S. Can you post the PGN for the game please?

i was watching this game, but the position was too complicated that i left without watching it

Bb4 

It is easy for black to win.

No solution?

...Bb4

Cutting off the road

Rc7, black will draw the game