Matovinsky Gambit
Owen's Defense
1.e4 b6 2.d4 Bb7 3.Bd3 f5 4.exf5 Bxg2 5.Qh5+ g6
Black's early ...f5 opens the kingside, and White's Qh5+ shows why it's dangerous.
Practice this lineThe idea
After 3.Bd3 f5 4.exf5 Bxg2 5.Qh5+ g6, Black has grabbed a pawn and is threatening the rook on h1, but the kingside is wide open. This line goes back to Greco's 1619 writings, and Christian Bauer calls 3...f5 simply suicidal. It's in the trainer so you know how to punish it.
Plans for White
Play 6.fxg6, threatening gxh7+ with a discovered attack. White is happy to give the rook on h1, because the attack on Black's king is worth much more. Keep checking and bring the bishop to g6.
Plans for Black
After 6.fxg6, every choice is difficult, and the natural-looking 6...Nf6 loses to mate at once. In practice, Black should avoid 3...f5 altogether and play ...e6 or ...Nf6 on move three instead, keeping the kingside intact.
Watch out for
For Black, mate. After 6.fxg6 Nf6?, 7.gxh7+ discovers check from the queen, and after 7...Nxh5 8.Bg6 is mate. See the trap.
For White, missing the follow-up. The rook on h1 is attacked, and a quiet move gives Black time to take it and survive with extra material.