The Eternal Crusade is a hypothetical name at the moment, but it is a new grand scale PVP game mode, with 12vs12 or 15vs15 players. I have to emphasize, that the server stability and reliability are the number one criteria, when implementing this content. 


Read and support my comprehensive forum thread, which solves the number one problem is PVP, and also has the 7 Tenets, of how to improve PVP (this new Eternal Crusade game mode is an element from it): PVP number one problem, 7 Tenets of how to improve PVP


The basics are the same, as in a standard PVP game, we need a big arena, to accommodate so many Space Marines. Class limitation number should be increased, the players can take four Tacticals, Snipers etc. in the Eternal Crusade, 


It should be an objective game mode (like capture and control), with huge battle, cause they are more players. If the devs will implement this grand scale PVP mode tens of thousands of new players will join the PVP scene, because it would be a truly iconic Warhammer 40k experience. 


Like in PVE in the background, there should be also battling going on, between the Imperium and the forces of Chaos, so it would feel, you are  in a major war, while the PVP match is still in a closed arena. This would only be an immersion element, if you check your surrondings, the Imperial Guard would be in close combat with the cultist. Naturally there should be more grenade and ammo boxes.