So I wonder if anybody has thought of legion rules much as the rules for space marines from Deathwatch. I did with my group right from the start and this is our preliminary idea
Legion Rules
Death Guard: +5 Toughness, +3 Wounds, starts off aligned to Nurgle, you dont get your power armor bonus to speed but you can never go below 2 for speed, can never remove power armor.
Thousand Sons: +5 Willpower, +1 Psy Rating, Must be a Sorceror, starts off aligned to Tzeetch, immune to mutations of all sorts, can never remove power armor,
Word Bearer: +5 Willpower, +5 Fellowship, gain the Cant of Lorgar (only if champion) from the Achilus Assault under the Dark Apostle entry,
Alpha Legion: +5 Perception, +5 Fellowship,
Night Lords: +5 Perception, Fear (1)
Black Legion: +5 to two stats of choice, can be aligned to any of the gods.
Iron Warriors: +5 Willpower, +5 Perception, gain paranoia for free, gain Tactica (Siege Warfare)
World Eaters: +5 Strength, +5 Weapon Skill, starts off aligned to Khorne, gain frenzy from the start.
Emperors Children: +5 Agility, +5 Willpower, starts off aligned to Slaanesh
for the four legions that start off aligned. You start after full character creation. Your number starts as 5 above what is needed to be aligned. If you get to a different alignment you lose all benefits of being from your legion except for the stat bonues. You can never get marked by that god and can never get aligned with them again.
So here are the preliminary rules for legions i'm working on.