Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...a6/4. Ba4/4...Bd6

4...Bd6: Neo-Steinitz Defense

Black instates the Neo-Steinitz Defense by playing 4...Bd6 in the Ruy Lopez. Unlike most main lines of the Ruy Lopez, this is considered way too off-beat for Black in high-level play, but is credited as a steamroller for beginners. Before we learn about its pros and cons, there is one more note of interest: most games with this come from the Morphy Defense, but some derive from Bd6 first, and then a6.

Pros

Flexibility: The Neo-Steinitz Defense is good for defending against most lines white usually does, like d4 or c6. The main idea of the Neo-Steinitz Defense is to get all of your pieces off the back rank to castle (usually queenside but some sidelines involving King side castling) and relieve pressure.

Space: Another idea that Black thinks about playing this variation is reducing tension in terms of space. Usually Black plans to play d6, hence the name "Neo-Steinitz Defense."

Cons

Central Strike with f4: There is no way to stop good counterplay with f4 when White plays d3 and Ng5, where White plays f4. I would recommend f6 instead of exf4 because your Knight become useless as a roadblock.

Evans Gambit style with 5. b4: One dangerous sideline of the Neo-Steinitz Defense that beginners need to look out for is 5. b4 and transpose into an Evans Gambit. I recommend taking the pawn and retreating back to d6 after 6. c3.

Conclusion

This is good for defense, but it forgets to attack.