Veterans of the Zelda series should recognize North Hyrule. It's known for a few memorable scenes: the bridge seen in Super Smash Bros. Brawl and Super Smash Bros. for Wii U, a showdown with Moblins, and a great finale between Link, Zelda, Epona, and Ganondorf, from horseback combat to epic one-on-one sword fighting. Kakariko Village should also be at the bottom of the Goron mountain.
Like before on the Death Mountain level, you'll be on your own at the start as Lana.
Introducing Agitha, the bug collector
You'll notice on the map that about half of the area is blacked out. If you've ever played Twilight Princess, you should recognize this as the area in which Link transformed into a wolf for the first time. Before anything else, you have to save a girl with an umbrella. On the 3DS and Switch, remember to unlock owl statues in order to use your Ocarina to help you travel quicker.
On the south end of the map, take out one base before going further to the corner southwest of the map to trigger a cutscene. She'll introduce herself as Agitha. In Twilight Princess, she has Link collect bugs in exchange for prizes, from rupees to a giant wallet. Here, she has a playable role, using her parasol and love for bugs in battle. For now, protect her as you'll be going into the twilight area.
Veterans should remember Midna herself. She plays Link's companion and is the only character with a much larger role than Navi. If you can get to the end credits of Twilight Princess, you'll see her true form. In this game, she's trying hard to dominate this level. There will be another cutscene in which she stubbornly keeps Agitha's butterfly.
Midna is only as strong as she is because of her twilight bases, so retake all the bases while protecting Agitha. Be mindful of your Allied Base too, as Midna will try to drive you mad with her many army officers.
A bridge to the end
Once Midna's army runs out of steam, finish protecting Agitha and take all the bases, then go to the bridge area past Midna and attack her final base. Midna's power at that point should have diminished and should give you a chance to take her down to end her rampage. The cutscene shows Lana clearing up the issue, wanting to close the "Gate of Souls" and Midna agreeing to team up on the next level. This includes finally letting Agitha's butterfly go.