Nintendo is showcasing gameplay of the new Xenoblade Chronicles 2 Challenge Battle Mode in today's Treehouse E3 livestream. We now also know that Shulk and Fiora are going to be playable Blades in the mode. All of this will be in the Expansion Pass content coming on July 15 this year.
In Challenge Battle Mode, you talk to a Nopon Arch-Sage who will give you challenges to complete. As a reward, you're given new treasures and items, and "even something else beyond that," according to Demetrius Boggs, Product Marketing Specialist at Nintendo who showcased the demonstration. He stressed in the gameplay demo that Challenge Battle Mode is going to be very tough, with you fighting waves of enemies from which you collect Ether Cubes. These cubes fill up chests that you can unlock if you beat the challenge, with more chests becoming available the more cubes you pick up.
Shulk and Fiora will act as blades in the Challenge Battle Mode. When using Shulk as a Blade, you'll get to use his Monado sword. Fiora will give you use of her Well-Used Blades, and serves as a healer with wind element abilities. This makes her a great attacker. All of this extra firepower will be necessary, as a large number of the enemies you'll face in Challenge Battle Mode's waves will be enraged, and able to easily deliver one-hit-kill attacks, a large part of that difficulty stressed. Some of the challenges even restrict you to a certain level cap - in the demo, Demetrius was level 75, but the challenge he played brought his and his blades' levels down to 30.
What about that aforementioned "something else"? Well, one of the rewards you get from these unlockable chests is Noponstones. You can use these to unlock new outfits for your characters, with a specific focus in this demo on Disguised Pyra, a secret outfit for Pyra long-desired by fans. There are plenty of other outfits too, which are all a little on the pricey side, requiring plenty of play time in Challenge Battle Mode. There are plenty more outfits planned, and you'll be able to find out which when the content drops on July 15.