Steinitz Variation
Scotch Game
1.e4 e5 2.Nf3 Nc6 3.d4 exd4 4.Nxd4 Qh4 5.Nc3 Bb4 6.Be2 Qxe4 7.Nb5 Bxc3+ 8.bxc3 Kd8 9.O-O
Black attacks e4 with the queen from h4 and grabs a pawn, at the cost of king safety.
Practice this lineThe idea
After 4...Qh4, Black's queen hits e4 at once. The main line is 5.Nc3 Bb4 6.Be2 Qxe4 7.Nb5 Bxc3+ 8.bxc3 Kd8 9.O-O: Black has won a pawn, but the king has had to move to d8 and White is well ahead in development.
Plans for White
Open lines toward Black's king, which has lost the right to castle: Re1, Bd3 and the bishop pair give White a strong initiative for the pawn. Black's queen on e4 is exposed, and moves like Bd3 or Re1 can gain time against it.
Plans for Black
Get the queen to safety, develop with ...Nf6 and ...d6, and tuck the king away. If Black survives the initiative, the extra pawn can count. Trading queens is welcome, because it takes the sting out of White's attack.
Watch out for
For Black, the c7 square. After 7.Nb5, White threatens Nxc7+, forking king and rook, which is why the main line goes 7...Bxc3+ 8.bxc3 Kd8.
For White, the pawn. If the attack fades, White is simply a pawn down, so play energetically.