Hi Dev,
Please check on the castelan. I think its a bit error. 
Sincerely your masterpiece fans,
NicKing
2 Likes
Yeah, this happened to me too, idk it doesn’t actually make him unkillable or give him infinite shield
I think its cause of Min. Either She hacked me or hacked castelan. 
Its more likely the brogan or franc sharing his own buffs with himself or something
Its not brogan or Francoise cause I rarely use then (I don’t have brogan either) and it happened once to me
Happened to me couple times. When he was last man standing. He solo all 5 of my heroes left both times. It just an unlimited shield glitch
Yes he still received damage when we attack him. But the regen of his shield is crazy.
Quit crying and suck it up