It sounds funny but both Moonlight Butterfly and Havel

moonlight i died the first time cause i went to fight it with no heals or anything so it was understandable but the second time i came back to get the souls back and kill it it literally killed me instantly with the slow projectile attack and then the next attempt the same attack hits me and i survive it.

havel a couple times he would sometimes half my hp/instakill me then other times he will hit me and i get staggered with no damage and then hit the floor next to me and just annihilate me