I looted leandra's Spell, killed mangoth and got her diary and the blood. I never explicitly used the blood on the scroll, i recall thinking it might be an effect similiar to the destruction of the large blood stone.. but clearly its not

While watching play throughs I see that i'm supposed to have a spell/ability that removes a monsters immunity aura.. but none of my characters have it, that i can find
i checked all of my characters for the blood, no longer see it. I never sell obvious quest items, i store stuff in the homestead..
i checked all vendors to be sure it wasn't sold accidentally. nothing in my homestead either. did i miss a step in the progression, did it bug on me... or what

knowing what icon was used for her blood vial would help too
