Tibus' champions are sacrificed if a player stuns them.
According to another post...
Roger the Alien wrote:
I had a small conversation with WWG at facebook:
1. The heist ability of the thief is useless vs. the shadow boss because he has no discard pile (he sacrifices all of his cards) and there is no other use for it, correct?
1) it's not completely useless: you could stun a champion in front of Tibus, which would then go to his discard pile. Then you can Heist it.