To get an idea of how I write high-action scenes, I went back and reread a few of my battle scenes from the original (and very rough) draft of my novel. A few things immediately jumped out at me.
If you struggle with writing character's specific thoughts and actions during a fight scene, if the battle is more of a takeover - one side is clearly going to win - or if there's a lot of leadup to the battle that you want to include in the same scene or chapter, one option is to write the battle in more of a summary format. I did this with the second battle scene I wrote, where the army from one country, Sevania, is taking over Alandia's biggest trade city. I got inside the head of one of the people fighting - in this case, the only girl involved in the battle - for the leadup but the actual battle was written in a few short paragraphs. You can try this approach, throwing in, as I did, snippets such as "enemy soldiers were falling like dominoes" and how she could "see flashes of golden light from Miveerna's magic". If you're going to write this way, it's generally better to have it be a shorter, more one-sided fight that doesn't require as much detail. I closed with sentences including "the battle was over almost before it had begun" and how "within two hours, they had taken Yalda." (Keep in mind, this was a VERY rough draft, and so the examples here aren't my best work.)
For longer, more drawn out battles, I wholeheartedly agree with Ms. Levine's advice about creating a map. If the battle takes place in a castle, draw up a floor plan - nothing fancy, just the major walls, rooms, secret passages, et cetera, that will affect the fighting. If it takes place in a forest, you don't need to draw every tree - that's the fun of writing forest scenes, you can add in a fallen log or a stream whenever you need to - but you should include major landmarks like rivers too wide and deep to wade, cliffs or dropoffs, and major trails.
Once you've created your map or floorplan, I highly suggest making several copies, either on a copy machine or with tracing or carbon paper. It helps immensely. If you know how many scenes you're going to have in the fight or how many times characters are going to move, make one copy for each so you can plot out your character's locations.
One of the hardest things when writing a battle scene can be keeping track of where everybody is. Before you even set pen to paper you need to be able to answer the following questions.
How many characters are going to be your POV characters during the battle? If you're writing from third person omniscent, you still ned to know this, even though your POV characters may be more numerous. If you're writing from several close-focus third person or first person POVs - switching only at the end of a scene or chapter - then you should generally limit it to the people whose POV you've been using for the rest of the book. Adding a new POV character in the middle of a battle scene may confuse readers and slow down the pace. Introducing a new character altogether should just be illegal.
Where are all your POV characters when the battle starts? On one of your maps or floorplans, pinpoint the location with a seperate colored pen or pencil for each POV character. Write "Beginning of Battle" or "Starting Point" or "Scene One" or whatever you want on the top of the page. Write "The-Place-Where-The-Whole-Darn-Thing-Gets-Started" if you want, but just make sure you know that this is the beginning of the battle.
Are any deaths going to occur in the battle? Who is going to die? Where is the death going to take place? What other characters are going to be present at the death scene? On another map, mark the place of death of the character who's dying his or her own color. (If they're a POV character, use the same color you did before; if they're not, use a new color.) Add in the people who are going to be present at the death, again, assigning each character there own color. Don't add any other characters yet, and don't number this map. You can write "So-and-so's Death Scene" if you want, but don't number it. Set it aside.
Where is everyone going to end up at the end of the battle? If it doesn't really matter and no one needs to be in a certain place for the plot, you can wait and see how it works out. If only a few characters need to be in a certain place, mark them down and leave the rest to end up where they will. Write "end of battle" or some such name on the top and set it aside.
Okay. Now, you have some things to work with. You know where everyone is at the beginning of the battle, where you need to get them for the death of so-and-so, and where you need to get them from the end. Decide when any deaths you've planned will fall as far as time, and then use your remaining maps to chart the significant movements of characters as you get them where you need them to go during the battle. Add in supporting characters, if you want. Have characters moving in groups. You should end up with a wonderful color-coded conglomeration of charts. (By the way, I hope you've got a reference somewhere for your colors, as in, green = bob, purple = dave, blue = phil.)
So, now you know where everyone's going to be, and now you have to write the thing.
Obviously, you can't use the summary format for something so big and that you've spent so much time on. You're going to have to get inside character's heads more and describe specific actions. This can be tricky, so don't worry if you don't get it right the first time around. Every time you try again or rewrite it you'll improve, until writing battle scenes becomes as easy as any other aspects of your writing.
One of the things that I find the hardest about writing battle scenes is avoiding repetition. Before you begin, I reccomend doing a synonym search (www.thesaurus.com is a good place) on words like sword, armor, soldier, blow, stab, block, and other words that you'll be using frequently. Make a list and save it as a new document or write it down and put it where you can easily see it while you're writing.
There are other things to avoid repeating, too, such as sequences of events or character's thoughts. Every oponent shouldn't be dispatched with the same tactics - mix it up and describe different strategies, movements, and methods. If you're writing a large battle scene with relatively equal forces on both sides, you can devote more time to describing the action between two people since most soldiers won't have to worry about fighting more than one or two people at a time. If one side outnumbers the other four to one? You're probably feeling overwhelmed trying to keep track of all the people bearing down on one character. Don't worry, that's exactly how the one character feels as he tries to block blows - it's going to be easy for you to slip into his mind, now. Write about blows coming so fast that he can't tell where they're coming from, about all his enemies seeming to merge into one ubitiquous force, to cut down on having to keep track of whether Soldier #1 or Soldier #3 was cracking his ribs while soldier #2 kept him distracted.
Action scenes are primarily composed of, well, action; however, if you're feeling like you need some dialogue, fear not! This can actually be a very helpful tool. If you allow the specific jabs and swordthrusts to fade into the background, it can take some of the monotony out of depicting each one. Remember when you decided that Character A and Character B would fight together for a brief span in Scene 7? Well, that was sheer brilliance on your part, because you've got two characters who, presumably, can communcate - hey presto, dialogue! If they're old rivals facing each other in battle, they can trade insults in the same breath as blows, and as long as you imply that they're fighting, you only need to point out a few specific moves. If they're friends, they can discuss how they're going to get out of this situation or what they need to do next as they hack through rows of enemies.
Another tip is to imply swordfighting through onomatopoeia that punctuates dialogue. One example of this is a scene I wrote in one of the first battles of my book. My character switched sides in the middle of a war, and ends up facing the queen he betrayed - who's also his ex-lover - in battle.
"They always turn on you when you least expect it.” Wham. “And Flamefoot, I thought maybe you cared.” Clash. “But, then again, they always say it’s the ones closest to you that you have to watch.” Bang.It's clear that they're fighting, but I don't have to describe each individual move.
As for keeping things fast-paced, I only have two pieces of advice. First of all, if you're like me and are addicted to description, don't worry. There have to be some adjectives in there besides the ones used to describe the force behind a sword. Just remember that when writing description, if well written, short sentences comprised of a few adjectives, a verb, and a subject, can pack just as much punch as a collosal one like this.
My other piece of advice, which will help battle scene writing all around, is to get into and excited about what you're writing. If you get really into your story, then you'll be just as anxious to finish writing the end of a chapter as your reader will be to finish reading it, and so you'll naturally shift into a faster pace of writing. Basically in writing, whatever you as the author feels as you are crafting your book, the reader gets a watered-down version of, so make sure that above all else you're keeping yourself on the edge of your seat.