This is a MUST MUST MUST know basic Rook and Pawn endgame. Black to move! How should black proceed?
H2 and then Rook has to move off of g file or black's king becomes immune due to the newly empowered black rook!
The only counter I can see in this line is that white tries to keep the king on f2 so that Rg1 is mate after h2, but black should be able to always counter this with a check from the flank.
Well, it obvious what black should be aiming for, I am just not quite sure how to do it.
My initial thoughts are this- I don't see any holes in it, but it is easy to overlook something:
1.....Rb3+ 2.Kf2 Ra3 3.Rg7 Ra2+ 4.Kg3 Ra3+ 5.Kh4 h2 and now black has the set up for stalemate. He just has to keep checking the white king trying to force white to capture the rook.