User blog comment:Khalael/Building a Connection MkII/@comment-3341288-20110719005949/@comment-10514705-20110719192431

The Revenant Tigers original purpose was one of eradicating Xenos threats. Their primary enemy was the Eldar, and they were frequently used to eliminate them if they were found on Maiden Worlds. The Revenant Tigers also participated in a couple of Hit and Run attacks against a few different Craftworlds, so that they could better understand the mindset of their enemy (even if they never gained anything from the attack), so that they could slaughter them more efficiently when they were fighting on Eldar Maiden Worlds.

However, at some point near the beginning of 001.M41 the chapter ended up in an impromptu alliance with the Eldar in order to stop a large Chaos Incursion. From their on in, the Revenant Tigers became sympathetic towards the Eldar. As their purpose was to kill Eldar, the Inquisition saw their new and more frequent alliances with the Eldar as signs of heresy. Thus, their fate was sealed and the Prophetic Forgiven were eventually sent to exterminate the chapter.