The Bissler wrote:
While we are talking about Chaos Marines, why is it the case that you can't buy Rhinos and Land Raiders in the specific lists, only the vanilla Chaos Marine army and the standard Chaos list? Could these be added into the Support Cards as well?
Sure you can

You can take any support/special card from Chaos Space Marine list to codex list, it's stated in each divinity century description:
Example:
"The Thousands Sons Century may take support & special cards from the Chaos Marine list."
and for codex (aka Iron Warriors, Word Bearers), it's written page 23 "Legion Excommunicate Traitoris", second paragraphe:
"
All of the Legions may purchase Special & Support Cards from their Codex list, in addition to the unique Cards for that Legion. They may also take Company, Special and Support cards from the Chaos Marine list. However, as with Power-specific minions, you have to purchase a Legion Company Card in order to purchase a corresponding Legion-specific Support Card. In the interest of organization, all Chaos Undivided unit descriptions have been added to the standard unit descriptions."
I think that some restrictions on those codex lists should be changed:
- Obliterators should be also picked by Iron Warriors, the fluff clearly explained that they appeared first in that legion, not only in Black Legion (that should get another specific unit)
- No Cultists for Word Bearers should not exist too:
" The Word Bearers have been known
to have a massive cultist base, and have used cultists and insurgents since the Great Crusade. However, unlike the Alpha Legion, the primary use of cultists is as cannon fodder and distractions. "