I've had issues with Rotos in both arena and campaign now where his A3 won't ignore unkillable buffs and it won't block revive always either. It does work sometimes but not consistently. The worst part is if that champion still revives via a passive such as sikara in campaign and tormin in arena in my case, you can't target those champions anymore and are just stuck force closing the app. As for the failed attempt at ignoring unkillable buffs, I've seen it fail against both Sir Nicholas and Skullcrown, both of whom were fought in the arena.