0.6.20 First creature and sixth creature start battle dead bug?

At the start of battle my first and my sixth creatures start battle dead. The history log is empty. I tried out different specs and everytime my first and sixth creature start battle dead. I read the traits of every creature in Perdition’s team but there was nothing that could trigger what happened (Plus if it was a trait it would probably be in the history log)

Update: it also happens against other bosses
Update: 2 It happens in normal realms too. I haven’t changed anything to my team and it was working fine before. It started behaving like that after fighting bosses.

I think it was a weird way a diabolic trait worked with revenant king. after equiping an artifact to my creatures they ended up fine