Bogo-Indian defence
1. d4 Nf6 2. c4 e6 3. Nf3 Bb4+
White plays the queen's pawn to d4. Black develops the knight to f6. White advances the c-pawn to c4.
Black pushes the king's pawn to e6. White develops the knight to f3. Black develops the dark-squared bishop to b4, giving check.