I may or may not have found a way to get a few warriors on the sly. You can message the support staff and say you decided to get to 8*'s and sacrificed some warriors, but that your didn't understand how it worked, so you sacrificed them on the main home base screen (how youd normally sac a warrior) instead of when prompted in the "upgrade me" door.
I may or may not have used this to get 6 new legendaries (make it a multiple of 3).
You may or may not be able to use this to get Back Trieu, Yi Ho and Alboin.
But I can neither confirm nor deny anything, just don't abuse it and be sure to know it's a one-time thing, so make your choice count. Don't post it on the main forum either.
If you catch my drift.