M&M: Heroes VI - Fan Manual
I haven't come across this before but a diligent team of Might & Magic: Heroes VI fans has put together a fan manual for the game. Apparently they've done this before for the King's Bounty games. I haven't downloaded it myself but at 268 pages, it sounds rather comprehensive. Details and links here on the Ubisoft forums.
Information aboutM&M: Heroes VI
SP/MP: Single + MP