Diabolically Evil Twisted Puzzle


It's a pity it is White's turn, Black has forced mate with (Nxd6), as all White can do is delay mate by Blocking with his rook, and then possibly block with the pawn if we assume that the pawns are actually moving that way.
It would have been more challenging if it had been black to move and mate in 3.

"Diabolically evil" is a bit much. It's not so much a hard puzzle as a mind game.
Is it me, or do self-styled trick puzzles always seem to involve pawn promotion?
This idea came from a puzzle a friend presented to me a long time ago.