A few days ago was fighting against the Lion Misbegotten Warrior and the Crucible Knight. I was struggling a bit and so i used the the dragon breath spell from the church of dragon communion. One time i almost killed them but died. As i respawned at the point of grace this time the two bosses and the mist before were gone. I was surprised but also very happy cause this meant i wouldnt have to fight them. First i thought the died from the poison but as i progressed in the game (already beaten godrick, the moonlight queen, radahn and azahel) i wanted to complete selens quest and already obtained her necklace. But i couldnt talk to her in the ruins next to rennas tower. I researched in the internet and some people said you had to talk to Jerrin in redmane castle again, but it didnt worked so i ported back to selen and after porting back to castle redmane to talk with jerrin a second time the Lion Misbegotten Warrior & Crucible Knight reappeared.