This was pointed out on another forum and I took another look at my Vigilus Ablaze book. There's something interesting about the Renegade Chapter section that I think virtually everyone is overlooking because the wording is a little strange and the second part reads as normal so everyone skips the first statement. Here is the relevant section of Vigilus Ablaze:
Vigilus Ablaze p196, "Renegade Traits wrote:
If your Chaos Space Marine army is taken from a Renegade Chapter, you can either use the rules presented in Codex: Chaos Space Marines (e.g. they can use the Legion Trait ability and gain the Dark Reavers trait), or you can use the rules presented in this supplement. If you choose to use this supplement, and your army is Battle-forged, all Daemon Prince, INFANTRY, BIKER, and HELBRUTE units in a Chaos Space marine Detachment gain a Renegade Trait, so long as every unit in that Detachment is from the same Renegade Chapter. The Renegade Trait gained depends upon which Renegade Chapter they are from, as shown on the right. For example, all such units in a BRAZEN BEASTS Detachment gain the Rend the Foe trait.
Seems straightforward and normal right? But look closer: The first part says you can choose a trait
if your army is taken from a Renegade Chapter. To my knowledge, this specific wording isn't used anywhere else. Now being a programmer I translated that statement to pseudocode:
Do you notice that first part? That is conditional. It must be satisfied to move on to the next part. Now it is very likely this is just the typical bad wording from GW and it works like everything else but maybe, just maybe, that first part is intended and your ARMY needs to be from a Renegade Chapter in order to unlock the traits via detachments when Battle-forged (the second part of the condition). Now, hear me out before flaming: This MIGHT be why the Renegade Chapter traits seem to be way better than the Traitor Legion traits; because to unlock them you not only need a Battle-forged army but you need your whole army to be taken from a Renegade Chapter i.e. no taking a Red Corsair battalion with a Black Legion army to farm CP.
Certainly by RAW that is what this is saying if you actually read the first sentence and apply it as an If/Then statement. That first condition must be met before you can move on to the next part which allows you to pick a trait from C:CSM or Vigilus Ablaze.
What do you think? Bad writing, or has everyone missed a major change?
Some more notes:
* "Army" is defined on page 240 of the Core Rulebook where it states your army must be organized into Detachments. Logically, for your "army to be taken from a Renegade Chapter" your detachments would need to be as well.
HOWEVER, some points to indicate this is just bad wording:
* The first section p196 in Vigilus Ablaze states "The rules presented in this section are intended to be used in addition to those presented in Codex: Chaos Space Marines if you have chosen to take any Renegade Chapter Detachments. The following rules apply": and then proceeds to list out Warlord Traits, Relics, and Stratagems.
* Under "Abilities" it states "Renegade Chapter Detachments gain the following abilities:" and then lists out the "Reavers and Despoilers" ability (which does specifically say Detachments) and then the Renegade Traits section (which as above first mentions "army").
Now it could be that this is half and half. That is by RAW, if you have a Renegade Chapter detachment, but not army, they would still get Warlord Traits, Relics, Stratagems and Reavers and Despoilers, but NOT Renegade Traits (as this applies another conditional).
FWIW I did email GW's FAQ inbox.