Kulemak invitation bug

Good day, i killed the final form of kulemak's invitation boss and died at the same time. Rare loot has gone when i woke up at the check point and i had no chance to contact with the npc to get the new lich ascendancy.
Could u support me please? I'd be happy even if u could reset this stance for me completely so i can fight him once again. Or if there a better solution i'd be happy to hear