Chess Opening Theory/1. d4/1...d5/2. c4/2...Bf5

=Queen's Gambit Declined: Baltic Defense=

2...Bf5?!
A rarely played move against the Queen's gambit, which has similarities with whites London-system. This move develops the light-squared bishop to control the e4 square with a piece and therefore wants to deny the e4 push from white. This declines the gambit in a way, where black can't reinforce his pawn on d5 and isn't able to control the e4-square with a pawn after cxd5.

This is less common as white has no problems to seize an advantage in the game.

Theory table
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'''1. d4 d5 2. c4 Bf5'''