was my first thought. Knight and pawn moves let the king go too far. Then, I saw I could sac the Bishop and give black several moves. Then I looked at queening the h-pawn but black gets in the check with his pawn. So that left the only other idea that turned out to be the solution.
(1) Have to get an idea from apparently redundant pieces
(2) Perform a short calculation
(3) Trust yourself and Just do it