SoC hands you several account-wide resources that are all genuinely scarce, and the biggest mistakes new accounts make are almost all about spending one of these too early or on the wrong unit. This guide covers what to save, what to spend, and in what order — reworded from long-time-player consensus, not the game's own tutorial text.
Castalia — the scarcest resource in the game
Castalia unlocks the second branch of an RK skill choice, letting you eventually run both options instead of one. It stays scarce even for year-one accounts — don't expect to have more than a handful at any point.
Never spend it on anything below Legendary rarity, and be selective even among Legendaries — reserve it for units you're certain are long-term mains.
As a new account, the safest move is to not spend any Castalia at all until you understand the tier list and your own roster. Every guide's specific 'take both options' calls (noted on the relevant character pages) are worth banking Castalia toward; spending it blind before you know what you're building is the single most common regret long-time players report.
Hope Luxite and the pull system
Hope Luxite is the pull currency — spend it on unit and Astral-gear summons only. Shop cosmetics and name-change items are consistently called bad value, even for spenders.
Pulling for a unit's Astral (signature) weapon is normally not worth it for a free-to-play or low-spend account — the exception long-time players make is for a unit they've confirmed is a top-tier, long-term main, where investing further into that one unit beats spreading resources across several good-but-not-great ones.
The pull system runs on a roughly 2% legendary rate per pull, a soft pity around 100 pulls (guarantees some legendary, ~50% chance it's the current debut unit), and a hard pity around 180 pulls (guarantees the debut unit specifically). Going all the way to hard pity is only recommended for a unit you're certain is worth it.
Unused pity carries forward to the next banner if you stop pulling early — a banner you don't fully commit to isn't wasted, since the partial pity banks toward whichever unit you pull next. Plan pulls around this: a near-miss on a unit you don't need still leaves you closer to guaranteeing the next one you do.
Talent trees — the account-wide stat boosts
Each of the five classes has its own talent tree, and the far end of each tree gives a flat stat boost to every unit of that class account-wide, regardless of which specific units you own.
Priority order by consensus: the physical-attack-for-all-roles keystone first (reached through the Seeker tree), since most of the roster attacks physically; then the equivalent magic-attack, HP, physical-defense and magic-defense keystones (through the Watcher, Breaker, Defender and Destroyer trees respectively) — magic defense is called out as especially valuable since bosses hit hard with magic damage.
For the shared Tactical Point (TP) trees: prioritise initial-TP nodes over max-TP nodes (max TP is rarely actually reached in a fight, so it's a lower-value investment), and prioritise the AoE nuke tactical skill (reached through the Destroyer path) early — it accelerates clearing content at every stage of the game. The boss-oriented tactical skills (a faction-wide buff and a group heal/buff, reached through the Sword of Convallaria and Watcher paths) are worth pushing next specifically for boss content.
Don't rush any tree's most expensive final nodes — the cost curve is steep, and a broad, low-cost spread across several keystones beats maxing one branch early.
Memory Shards and star level
Memory Shards raise a unit's star level and are farmed for free once a day through Memory Retrieval in Crossing Worlds (a limited pool split across whichever units you assign) or earned as pull duplicates.
Most units are fully functional at 1-3 stars; pushing to 4-5 stars is a real investment reserved for units whose kit specifically needs it — a 'gives you a second body' unit, or a unit whose rotation only comes online at a specific star breakpoint (checked and noted on that unit's own page where confirmed).
As a new account with few Legendaries, it's fine to put whatever units you have into shard farming — the opportunity cost only matters once you have enough units to have to choose between them.
Everything else — engravings, gear, and general spending
Engravings: the Sword and Wand types are used by the widest range of units and run out fastest — spend the Pentacle and Cup types more freely, since they see less demand.
Legendary gear becomes abundant later in the game and loses value over time — feel free to use it on whoever needs it early rather than hoarding it.
Never push a non-Legendary weapon to max level — the investment cost doesn't pay off compared to spending the same resources on a Legendary weapon.
The overall theme: the account that saves its Castalia, Hope Luxite and talent stars until it actually understands the game ends up ahead of an account that spent them immediately, even accounting for the head start immediate spending gives.