She's also got a pretty interesting kit. Effectively, pairing her with different partners will enable her to reduce the elemental resistance of her opponents. So, for example, if you have a Hydro member in your party, then using them in conjunction with Xilonen will enable you to reduce the Hydo resistance of your foe. This is consistent across all elements.
If you pair her with three other Geo characters, then she'll also buff normal and plunging attack damage, which is pretty cool. And she's capable of restoring Phlogiston and triggering Geo damage of her own. As with all Genshin Impact characters these days, you need a doctorate to truly understand the extent of her combat capabilities, but she looks pretty fun to use.
Elsewhere, the update will also incorporate some pretty major gameplay improvements, including the ability to skip some of the Spiral Abyss depending on your progress in previous updates, and better crafting and Relic filtering features. HoYoverse says more smaller updates will be announced closer to the update's release, which is scheduled for 9th October.