1. Read fantasy books that have battles in them.
Yes, I know that this is pretty unoriginal, but its true. Us writers learn our craft from reading! I am in no way saying to copy what the author of the book says in battle, but study the wording he or she uses. Look at the literary devices used. Think about the "battle moves" the warriors use, reactions to pain, and things like that.
2. Do research.
Research the time period your book is based in. Even if it is fantasy, it is still based on a time period. Research about weapons and what medicine was like. Remember, you want your battle scenes to be realistic! Also, if your book is set in a medieval time period, you might want to learn how to fence and shoot a bow and arrow, even if it is just through YouTube. :)
3. Write.
Yes, this is straightforward, but the scene won't just appear on the page. :) Closing out of Pinterest does indeed help.
4. Rewrite.
Battle scenes can be hard to write. I mean, there is bloodshed and that emotion of loss of human life should be carried through in some way. Battle must not be taken lightly. Take the time to heavily edit your battle scenes.
5. Know your POV character.
To artfully convey emotion in the heat of the battle, knowing your POV character thoroughly is key. How does he react to killing other creatures or humans, even if it is to defend his cause? Does he have high pain tolerance? A weak stomach? Make sure to not only describe the battle, but also the emotions of your character.
6. Describe.
This can be a touchy thing to do, depending on your target audience. But, the fact is, you may have an exact image, or movie, in your mind of what your battle looks like, but your reader doesn't. You must tell them exactly what it looks like!
Resources that Have Helped Me:
Courage by Molly Evangeline - this has some great battle scenes that made me go back and rewrite mine after I finished reading it. Whew, it is intense, but such an amazing book!
Lord of the Rings movies - there are A LOT of battles in this movie and give some great examples. Beware, it is violent.
I hope this helps you!
God Bless!
Alea Harper :)