Hornworking

Hornworking is a branch of magic that involves using the horns of demons and other creatures to direct spell energy. While hornworkers inevitably learn a number of potions, tinctures, and home remedies involving the horns of certain creatures in the course of their work, such alchemy is typically not a hornworkers primary goal. The most powerful form of hornworking involves crafting the horns they collect into magical objects that release spell energy when blown. The magic relies on both the inherent magic of certain horns and principles of magial notes similar to those that power bardic magic.
Crafting a magical horn is a rather time-consuming process that starts with acquiring a horn. Since the horns of different types of creatures are required (or at least more potent) for certain types of magic, this can be the most time-consuming part of the process. Some hornworkers prefer to do this the "old-fashioned" way, hunting down and killing the horn's owner themselves. Others rely on Weirdmongers and other specialist to track down their materials.
Once the horn is obtained, it's carved with magical runes and signals, treated with a variety of powders and oils, and subjected to various rituals at times and places dictated by the magical effects the horn will release when blown. Most magical horns have a primary effect that can be triggered by blowing just about any random note on the horn. Many, particularly those made for the hornworkers personal use, can produce additional effects when a particular series of notes is blown by a competent hornblower.
While there are certainly wizards who focus primarily on hornblowing and wade into battle with a bandolier of different magical horns strapped across their chest, most practice hornwork as a supplement to more versatile and immediate forms of magic. Wizards who practice hornwork alongside knot magic are particularly valued as ship's mages, especially if they also have a working knowledge of water magic or the rituals required by various sea gods.