The Raven's Request
Head to this quest marker to trigger another side-quest.
At the quest marker, a raven can be found. But oddly enough, it speaks and is asking for some items.
Accept its request and go fetch it some Spectral Shrooms nearby.
They can be found growing by a tree just south of the Raven's position.
After placing the Spectral Shrooms in the cauldron, it asks you to gather more ingredieents.
The Slime Extract can be obtained from slimes around the quest marker.
Next is the Muddy Mandrake. Head to the next quest marker to find it.
Take the Muddy Mandrake from the ground and an enemy will appear. Defeat it and continue.
The next part is a Swamproot Flower. Make your way towards the place.
Take the Swamproot Flower.
Place all the things you just collected into the cauldron. The raven will ask for one last thing.
Go to the quest marker to find the Eye of Toad.
The Eye of Toad is in one of the many barrels you will see in that place.
Add the final ingredient and the raven will transform back into a human. You can buy and sell stuff to her as she is a merchant NPC.