Blood Sap (the arrow piercing the orc on tree outside the Keep) ( 139, -12, 138 ) /waypoint 139, -12, 138
Deathrot Oil (-8, 1, 22)
Needed for the fight; she gets an invincibility that can hit through with it, however it heals her if you pop it before the invincibility pops. Make sure you save it until then.
If you are on the signature quest The Siege of Zek: Sacrifice (Solo), you can kill Rinis and Yallessulich in the same run, although you won't get achievement or chest for the Yallessulich on the quest kill (you can come back later and kill him for credit).