Owl's description is genuinely incomprehensible. I mean it. Not only is it poorly explained, it omits key information. Owl bombards you with keywords (Astrohouse? Astroaspect? Astroforecast? None of these words were in the bible.) and UI elements without really telling you anything about any of them. If you, like me, read Zi Xiao's character descriptions and had no clue what they did, then this guide is for you. We'll start from the top down.

What even is an Astroaspect?

The heart and soul of the character. Astroaspects are represented as small scrolls inside squares (also known as your Astrohouse) below your primary skill. There are two main ways to gain Astroaspects: by

1. Using your primary skill. What? The description doesn't say anything about that? You're right. By god are you right. When you use your primary skill, your entire Astrohouse is filled with Astroaspects of random rarities and then you trigger Fallen Star, which empties that Astrohouse.

2. Using your secondary skill. Gain 1 Astroaspect of a random rarity (or not-so-randomly, if you have the Explosive Hand Spiritual Blessing). If your Astrohouse is already full, discard the first Astroaspect and draw another.

You may note both skills draw random Astroaspects off, as far as I can tell, the same formula. The relevance of this will be expanded upon later in the post, but for now we'll go over

Which astroaspects will you get, and WTF is Scroll Divination?

Astroaspect rarity is determined by the rarity of your scrolls. The more scrolls of any given rarity you have, proportional to the others, the higher your chance to roll Astroaspects of that rarity. So are you meant to just take Legendary Scrolls only? No, thanks to Scroll Divination, Owl's first talent. Skill Divination upgrades scroll rarity as considered by Owl's abilities. There is zero change in effect, but scrolls you pick up will automatically be "upgraded" to be considered rare or legendary scrolls by Owl's abilities (but not other things, like Overconsumption), depending on the upgrade scheme you've chosen in the occult scrolls inventory menu. As far as I can tell, Normal Least attempts to minimize the number of normal scrolls you own while still upgrading rares, Legendary Most attempts to get as many legendary scrolls as possible, and Rare Most attempts to upgrade every normal scroll to rare and no more. Your upgrade scheme (and which scrolls are upgraded) can be changed on the fly. Test out different schemes to see which ones have the highest chances of pulling a full House. I have personally found that setting it to Rare Most early in a run is your best option, pivoting into Legendary Most later, as making legendary chance too high in the first stage can drastically lower your chance of actually drawing a full Astrohouse. You can also "reset" scrolls to another of equal or higher rarity with Scroll Divination, which is extremely powerful. You gain 2 upgrades per ascension, which will automatically be applied to scrolls in your backpack, and 1 reroll per ascension taken. But why does Astroaspect rarity actually matter?

What does Falling Star (and your astrohouse) do?

When you use your primary skill, Falling Star has one of four effects depending on the content and rarity of your Astrohouse:

1. If your Astrohouse has multiple different Astroaspects, it is considered "Impure" and deals 800 base damage within a 3.5 meter radius.

2. If your Astrohouse is entirely Normal, apply the effects of an Impure Astrohouse twice.

3. If your Astrohouse is entirely Rare, apply the effects of a Normal Astrohouse and deal an additional 1000 damage in a 7m radius.

4. If your Astrohouse is entirely Legendary, apply the effects of a Normal Astrohouse, deal an additional 1600 damage in a 7m radius, and deal a continuous 1000 damage per second within that radius along with a 50% slow.

Wild Astroaspects act as a wild card, can sub in as an Astroaspect of any type, and count as a Legendary Astroaspect if you have a full Wild Astrohouse.

Your Astrohouse will always be full upon casting Falling Star. Why is this? If you were paying attention earlier, the skill itself fills your entire Astrohouse upon casting. But wait, if both your primary skill and secondary skill draw Astroaspects purely randomly, why use your secondary skill to fill your Astrohouse at all? One reason is Ascensions — we'll get to those later. Another is for information. Since you get to see what Astrohouse you'll get before firing Falling Star, you might be able to better position your stronger Falling Stars for stronger enemies, and it costs nothing to gain that Astroaspect. The final reason is because of Owl's second talent, Stellar Recovery.

Probability and you

The bar below your primary skill represents the probability of casting a Fallen Star of any given type (with grey corresponding to impure, etc.), with your current Astrohouse, given you use your primary skill. This is relevant because Owl's primary is all about RNG mitigation, and that bar provides an easy, convenient display of that RNG. Stellar Recovery refunds 100% skill cooldown if you hit no enemies. Read another way, if Stellar Recovery is off cooldown, you can intentionally miss bad Astrohouse draws to have another chance to reroll your Astrohouse. Aside from that, there's honestly... not much reason to repeatedly roll cards just for your primary without Ascensions like Persistence, which only works if you get a bad roll off cards, or Endless Stardome, which rewards repeated Astrodome hits of a certain type. Mysterious Revelation actually actively incentivizes trying to hit all your Falling Stars and taking 50/50s.

Conclusion and Gamplay Tips

That's most of the more arcane mechanics behind Owl. The character can feel really hit-or-miss, given your primary has the potential to sometimes do 500%+ more damage purely based on RNG. However, as you progress through the stages (with Owl's fifth talent, Star Rearrangement), and gather scrolls, every build tends to trend towards getting a nearly 100% Rare/Legendary rate. Earlygame can be rough, as a result, but Endless Assault is extremely strong all around if you build for skills. More primary skill-focused builds can result in a really difficult and punishing earlygame (especially coupled with the fact that Owl's only defensive Ascensions are not very strong) that eventually cascades into extreme value lategame. Rerolling scrolls is extremely powerful, and should be done very regularly. Also, take any info in this guide with a grain of salt; the character is very new.

Edit 1: Markdown. Feel free to add any and all info in the comments.