You finished up the Obscura Tinctura Magica quest in Village Ruins. The Combo Master now has your potion ready. Talk to him and he will give you both the potion and the dosage instructions.
So you have to take out Mishirla... Deja Vu, anyone??? You will find Mishirla on the road southeast of town.
Now, all you have to do is coerce the patient to take his medicine...
The potion actually works! Mishirla gives you a sketch of Khormynth's Refuge and this quest is complete.
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