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I've seen that its rules exist, but not in which book or web supplement to find them. Where can I find them?
The rules for the Roc Pattern are in Imperial Armour Volume 12 - The Fall of Orpheus, from Forge World, p.151.
You can just about see this from the scanned table of contents (2nd image) on the FW page for the book. It's also referenced on the 40K Wiki.
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