Writing a fantasy novel is amazing because the possibilities are endless. However, sometimes it’s difficult to get your creative ideas on paper in a way which makes sense. This will go over a few common fantasy themes and give some ideas on how to approach descriptions.
Perhaps the most standout theme in fantasy novels is magic, but this can also be the hardest to explain. First, plan out some ideas of what magic your world will have. Will the magic be elemental, illusions, mind-control, telekinesis, or manifestations? The next thing to consider is how the magic system works. Are there wands involved? Perhaps the character can shoot out the magic through their hands, or maybe, the magic is contained within the character. Furthermore, will every person be able to use magic? Is magic something that can be learned, or is it genetic? Or maybe magic is only reserved for royalty. Adding rules and boundaries to magic will help make the novel more believable.
Once you have created your magic system, the second most important part is putting it into words. A common trope in fantasy novels is that magic is channeled, almost like working out. Characters will get fatigued, especially if the magic is particularly strong. This is a relatively easy way to write magic and can lead up to very suspenseful moments, like if a character is stuck in a dangerous situation and has to strain themselves to create one powerful spell.
Another way to write magic is if it is channeled through an object. This could be a wand, crystals, tarot cards or any other object. In this case, you will want to spend some more time describing said object. One example could be if the object heats up or breaks under lots of stress or use. You could also use a combination of the two ideas. An example would be if a character can use magic without the object, but the potency of the spell is increased with it.
Finally, here are some possible descriptions you can use in your fantasy novel. A boy is filled with rage. He feels as though flames are dancing under his skin, begging to be released. He complies, expelling the liquid flames outwards in a beam. A girl, standing a few feet away from said boy, throws her wand up in response. She clenches her eyes shut as she is hit with a blast of scorching air. But then, as suddenly as it appeared, the heat dissipated. A low hum was now audible in the air around her. She opens her eyes and notices a shimmering blue shield at the end of her wand.