What you were expecting to happen, and what actually happened?
Playing Explore (Blighted lands, PC). Was up against Infernal King with full traits. Immortal proced but the new Infernal King had no traits. I assume explore randomly chooses if a troop has traits and it rerolls that random chance on summon. So this only happens if you randomly get King, it randomly gets full traits, it randomly triggers on death, and it randomly doesn’t get traits on summon. Rare and not game breaking, but it is there.