Long before the mushroom war, there existed an ice elemental of great renown, Urgence Evergreen. He and the other elementals discovered that a comet filled with evil magic was headed to the planet, and in order to stop the comet, they created a crown, a crow filled with magic that could grant the wearer's innermost wish. Sadly, before he could use the crown to save the world, he got stuck under a block of ice and was forced to ask his student Gunther to wear the crown and save the world Urgence Evergreen, however, did not anticipate that Gunther's deepest desire would not be to save the world but to be just like Urgence Evergreen. Like Gunther, you have gained abilities similar in nature to Urgence Evergreen. Just without the sacrifice of sanity that comes with wearing the crown and being transformed into a different person.
You have gained unparalleled control over the field of ice magic, being able to freeze both living and non-living creatures into ice, transform ice into creatures, or use the ice to make weapons. You can also call storms of snow and ice or even shoot bolts of ice lightning from your hands. You also have access to a plethora of other abilities, such as flight, withstanding intense temperatures, seeing things beyond the ordinary, a sixth sense that could alert you to danger and protect you while not conscious, invisibility, illusion creation, and so much more.
While you are not limited to simply using ice magic, using other magic takes more time and effort than using ice magic. Your current strength in magic is enough to level a small country and will only grow as you get older, and with immortality, you have eternity to study and practice magic and grow in strength.