Chess Opening Theory/1. d4/1...d5/2. e4/2...dxe4/3. Nc3

= Blackmar-Diemer Gambit (BDG) =

3. Nc3
White has brought his minor piece into action and taken control of the middle. Simultaneously, he has put pressure on Black's e4-pawn, which Black must now try and defend. Nf6 or Bf5 would most commonly be used to defend the lone pawn, while e5 gives the option of a pawn transfer.

Theory table
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'''1. d4 d5 2. e4 dxe4 3. Nc3'''