Mate in 3

There are two thematic tries, 1.Sb1? threat 2.Sxc3, refuted by 1...Se2! and 1.Sc2? threat 2.Sb4, refuted by 1...Sxd3! The key 1.Rc4 threatens 2.Rd4+ Kc5 3.b4, and the two refutations return as defences: 1...Se2 2.Sc2 threat 3.Sb4; 2...Bd6 3.Qxb7, and 1...Sxd3 2.Sb1 threat 3.Sxc3; 2...Be5 3.Qf3. The problem combines three themes, 1) the Dresden theme, where a piece which provides a successful defence to a try threat is decoyed, so that in the post-key play the defence is replaced by an unsuccessful defence by a second piece; 2) Gamage unpins, where a black defender interferes with a pinned piece, allowing the pinning piece to unpin and mate, and 3) the Banny theme, a reversal theme whose pattern is Try A? 1...a! Try B? 1...b! Key! 1...a 2.B, 1...b 2.A.
A clear scheme, and the strong defence 1...Sxd3, giving a flight at e4, perhaps helps the solver find the key.

Rauf Aliovsadzade: Very nice! Logic plus strategy.

Juha Neitola: A combination of three themes with two matching variations.