Last weekend I faced an unusual line in the Teichmann.
1.d4 d5 2.e4 dxe4 3.Nc3 Nf6 4.f3 exf3 5.Nxf3 Bg4 6.h3 Bh5 7.g4 Bg6 8.Ne5 e6 9.Qf3 Bb4
My opponent did not seem very concerned about the threat of Qxb7 - in fact he seemed to be unaware about the possible white lines, he justed wanted to play something active...
I continued 10.Nxg6 hxg6 11.Qxb7 and got finally a draw after 11...Qxd4.
So how should white proceed after 9...Bb4 ? 10.Qxb7 does not offer anything after 10...Be4 11.Qb5+ Nfd7 12.Rg1 and white's position is a mess. So there is nothing else than 10.Nxg6 hxg6 11.Qxb7 Qxd4. 12.Bb5+ (which I played in the game...) brings only problems after 12...Ke7 (my opponent was so kind as to play 12...c6 aftre which I secured the draw after 13.Bd2 ) and now black can grasp the initiative after 13.Bd2 Qe5+ 14.Be2 Qg3+ 15.Kf1 Bxc3 16.Bxc3 Nd5
So white should continue 9...Bb4 10.Nxg6 hxg6 11.Qxb7 Qxd4 12.Bd2. Black only has 12...Bxc3, aftre which white can play 13.Bxc3 or 13.bxc3.
13.Bxc3 gives black a simple draw after 13...Qe3+ 14.Be2 Ne4 and the roles are inverted - black now sacrificed material and white needs to defens carefully.
13.bxc3 is stronger and denies black this simple draw, with following black options :
a/ 13...Qe5+ 14.Kd1 (+)
b/ 13...Qd5 14.Bg2 (++)
c/ 13...Qe4+ 14.Qxe4 Nxe4 15.Bg2
...c2/ 15...f5 16.Bxe4 fxe4 17.000
So this line seems to be a simple equalising line for black against the whole Blackmar Diemer as white does not seem to have much options. Talking about a disappointment !