Another Random Legion Power Idea
I don't even own Legion, so I'm not going to pretend to know exactly what they need from a balance perspective. The obvious take aways are that Legion has a very easy time getting the injure hit, but to compensate has just about nothing to help with the downing hit. Thematically though, it's pretty obvious that there's basically nothing aside from the cosmetics to bring home the Legion concept. So without changing them entirely, and trying not to disrupt their efficacy too much, I just wanted to give a low yield change idea:
As a secondary activatable skill (while FF is not running and on a cooldown) while at a breakable pallet, wall, or gen you can have one of your other available Legion members from the cosmetics you have available appear and preform the animation for you instead, with only a minor stun on your part. The action would still be privy to pop and brutal strength, and otherwise take the same amount of time to actually clear the breakable or start the gen regress. During that time you get a very short duration (3 secondsish) where the summoned Legion member takes on your red stain and terror radius instead of you. Full undetectable would probably be a bit too far. The end result is a combination of a small bit of extra efficiency that adds up over the course of the game from not getting locked into every break animation, and extra pressure only available occasionally to help against stronger loops. Lower uptime on the skill would be key to keeping it reasonable
Thematically, the Legion ends up seeming just a little more of a tricky, deceptive killer to the survivors. From the killer's perspective, you've got the smallest bit of teamwork on your side. It's just the other Legion personalities are adamant that you carry your weight in that trial, so it's more than just the entity that has a problem with you if you fail.