The Modernized Arkhangelsk Variation by Viktor Erdos

This exciting defence, which is characterized by the moves 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.0-0 b5 6.Bb3 Bc5, always amazed me. Quite an aggressive setup, Black is aiming to get very dynamic play (even at the cost of some material in many cases) in order to put a lot of pressure on White players as early as possible! No wonder that great, ambitious players such as Anand, Shirov, and Caruana, just to name of a few, like to employ it regularly. The variation also gained some attention at the Carlsen-Karjakin world championship match from 2016.
The Ark has always been considered one of the theoretically-heaviest defences in meeting the Ruy Lopez, though also the most exciting and definitely the most beautiful of all. It requires tactical vision, good calculation and memory, but not just from us – from the White side too. Let’s not forget that! I also must say that no good lines are absent of theory, so if we’ve decided to learn something “finally”, I argue that it can very well be an ambitious, double-edged line too!
I should also mention that this book is a complete Black repertoire starting from 3.Bb5 a6, the exchange variation being the first chapter. The publisher and me agreed on offering a full package, one that should prove useful for many years to come!