Praetus gets killed Immediately guild boss 2

I waited for months to get the pope. Got him this weekend. So I build him up,skill him, up promote him fully mythical artifact. Everything. Mythical gear. Im excited to get him in guild boss and he gets killed no matter where I put him with Elowyn and Delores. I even used Laya Elowyn overlapping and he’s dead before I get the whole team out. No matter where he’s at.
‘anyone got any ideas?