when playing blitz games, I get lately a lot of Euwe defenses where black fianchettos his queens bishop - a horrible strategy.
1.d4 d5 2.e4 dxe4 3.Nc3 Nf6 4.f3 exf3 5.Nxf3 e6 6.Bg5 Be7 7.Bd3 0-0 8.0-0 b6 9.Qe1 Bb7 10.Qh4 (diagram)
Many of my blitz opponents play these moves rather quickly, as if the Blackmar Diemer behaves like a normal opening...
In the above postion, black is hopelessly lost, eg 10...Nbd7 11.Bxh7+ (++) or 10...h6 11.Bxh6 (++)
Black's best ( if this word can still be used in this position ) might be to remove the target on h7 :
10...h5 ( diagram)
White's best reply here is 11.Rad1, but also an inferior move can bring white victory :
11.Bxf6 Bxf6 12.Qxh5 g6 13.Bxg6 fxg6 14.Qxg6+ Kh8 15.d5 (diagram)
White opens up many lines and has by far the most promising game.