Hey there. It's a simple question.
The wording of the Warhosts of the Pale Courts is the following
When seeking to represent the varied and enigmatic forces of the Pale Courts using the Warhosts system, the following rules can be used to customize the Core choices available to an Eldar Army. When using these rules no other types of Core choice may be selected as part of the detachment, but Auxiliary and Command choices may be selected as normal.
Does the Pale Court replace one of the Guardian Hosts shown on page 94 of the Eldar codex, thus getting the command benefit of Matchless Agility?
Using the Warhosts System
p94 of the Eldar Codex discusses a "Craftworld Warhost" as a special type of Detachment. Further in the next chapter, it lists special rules for the Detachment, making it unique from other types of Detachments.
In the Imperial Armor 11 book, there is no indication of a "Warhosts System" other than at the top of page 182. This seems to indicate that the Warhosts system is the one referred to in the Eldar codex - but it is not clearly defined.
no other types of Core choice
Only one core choice is listed in Imperial Armor 11. Why would this wording be used unless the pale court was part of the Eldar Warhost?
Auxiliary and Command choices may be selected as normal
Does this refer to only the Auxiliary and Command units shown in Imperial Armor, or does it indicate all of the ones available to Craftworld Eldar?
If I am missing something obvious, please let me know