For this level, unfortunately, you'll have no choice but to play as Impa only and Sheik only. Veterans of the series will recognize the upward trail to the Goron's City and to the area where Kakariko Village used to be.
In a cutscene, Impa is skeptical of Sheik as the person herself in history doesn't make sense. The fairy then comes down with the bad news: Darunia has gone on a rampage and has captured Princess Ruto. He also seems to be taking advice from Zelda?! Something isn't right, and it's time to right this wrong.
Watch out for rolling boulders!
As the first order of business, you'll need to take over the middle northeast and west base to stop the falling rocks. You should remember to take down numerous monsters until the keep boss shows up. Take down the keep boss to complete it. Take down Deku Plants with arrows along the way.
Darunia's blowing steam!
Your Allied Base is going to be in danger and only you can deal with Darunia's wild rampage! Attack him as you did with Volga and when his weak point (shown by the circle) is revealed, take him down and he'll temporarily stop.
Danger ramping up!
Sheik/Impa has an idea and needs you to protect her, so go to her and clear a path. At the same time, watch out for numerous officers and especially Darunia as he will make an appearance a few times. Sheik/Impa will move to the middle northwest base, as she'll use the rolling boulder to unblock Darunia's room. Unlocking Darunia's room will help stop Darunia from getting full fury health over and over again.
Last showdown with Darunia
Go to the top middle room after ensuring your Allied Base is safe and Sheik/Impa is back in full health. Make sure to take down two Poes, as they're the ones trying to rejuvenate Darunia, then take him down one more time to end this level and earn yourself some rest, as Princess Ruto will be free from capture.
Also, don't forget the bombchu operators as each bombchu can take down the base in an instant.
After getting 1,000 kills, go on the middle north west path where the deku plant is and shoot it with an arrow. There should be a ledge on the right. Unfortunately, you need the hookshot from the Twilight Palace level with Lana so you can hookshot up from that location. Come back with the hookshot before getting the skulltulla again.