Zeefzorpul is a fiendish little Imp, who is the nemesis of Grizelda the Hag.
Your first encounter with Zeefzorpul will be when you are looking for the apprentice of Grizelda. When you find the apprentice you will also see the Imp very briefly as it steals a recipe from his corpse.
Grizelda will then send you to get the recipe back, but first you will have to find out where the Imp is hiding. To do that you will have to seek out other Imps and beat his location out of them, either with weapons, spells or pets. Once you find an Imp that is willing to talk it will give you a Magic Flute and a Map leading to Zeefzorpul's hidingplace.
Now all you have to do is find the location marked on the map and play the flute. If you are in the right location, Zeefzorpul will be summoned by the sound of the flute.
The music from the flute will make the Imp give up Grizelda's recipe without any problems, but just as you get it, he will swoop down and steal the Magic Flute from you. Good thing you don't need it anymore.
Since you now have the recipe you can return to Grizelda the Hag.