Rules for medication

Instructions unclear I have killed the blight that has befallen the land and still have the potion in case I might need it later

This doesn't work because no matter how many potions you have, you have to save them for when you really need them. Then, you end up finishing the game having never touched any of them.

Then, you end up finishing the game

I.e. you do win...

A box of Deloxetine 60 mg gastro resistant capsules *not a potion

It's a distilled version that becomes a potion in your stomach. There are several versions of this, my favourite of which is "instant bubbling potion, just add water"