Honkai: Star RailCastoriceBest build, teams and other guides

Castorice is an extraordinarily powerful Remembrance DPS that scales with HP and does not consume Skill Points. Like Acheron and Feixiao, Castorice does not use Energy for her Ultimate, instead using a charge system that accumulates based on HP lost from allies, and Castorice's Skill and Enhanced Skill consume HP from all allies to be used. Her memosprite is Netherwing, a giant dragon whose presence alters the field and decreases enemies' All-Type RES. Castorice has numerous ways to boost her damage output and even provides defensive value for the team with some AoE healing after Netherwing departs the field, damage redirection to Netherwing to prevent allies from dropping below 1 HP, and a once-per-battle pseudo-Revive from her unique passive.

The ephemeral reaper graces us at last. Castorice is the character we're getting for the second anniversary of Star Rail, and she brings with her immense amounts of sakuga. Yes, she is also unfathomably powerful and good and all that, but have you seen those animations? Whatever they're feeding those lot, they should keep doing it.

Breaking from our usual coverage, we’ll address Castorice’s one-of-a-kind (at least at the moment) global passive first, since it’s a contentious part of her kit. Hearing 'global revive passive' makes it sound like it's game-breaking, but in the current endgame, for most, it will end up as more of a nice bonus to have than something mandatory.

When an ally receives a killing blow, they get put in a stasis effect where they can still act until the end of their next turn, but unless they get healed or shielded before that time expires, the ally will still die. It is not a replacement for a sustain unit, and is mostly a small fallback for when you've made a mistake in endgame content and would otherwise need to restart the fight (at least at the moment).

Back to the regularly scheduled breakdown, Castorice uses HP for dealing damage, continuing the recent trend of Amphoreus characters doing so. She actually has the single highest base HP value in the game, exceeding even Mydei, and even better is that, also like Mydei, Castorice does not consume any Skill Points to use her Skill. Instead of consuming her own HP to use her Skill, Castorice consumes everyone's HP instead; 30% current HP drained from all allies (including herself) to deal up to 50% Castorice's Max HP to a target enemy, and 30% to adjacent targets.

This HP loss is very important for Castorice's Talent and Ultimate. Castorice doesn't have normal Energy, instead having a charge system that's represented as a percentage in game. Whenever allies lose HP, Castorice gets 1 point of Newbud. When Newbud reaches 100%, Castorice can use her Ultimate to summon the memosprite Netherwing, a massive and imposing dragon. Newbud is not accumulated when Netherwing is on the field.

Whenever allies lose HP, Castorice and Netherwing's DMG dealt increases by up to 20%, stacking up to 3 times and lasting for 3 turns (essentially a permanent 60% DMG bonus). The exact number of charge she needs is ambiguous in-game, but at max Equilibrium Level, this amounts to exactly 34000 charge — or in other words, your team needs to sustain 34000 points of damage to fully charge Castorice's Ultimate.

This seems like quite a lot and puts a lot of pressure onto your sustain to be able to restore HP. Along with a Bonus Ability Trace later, this is the clear indicator that Castorice teams should only ever consider using direct Abundance healers, especially ones with huge healing throughput like Gallagher and Luocha. As the HP drain of Castorice's Skill is current HP, if you are not healing consistently, you will not be getting enough Newbud to use Castorice's Ultimate. Do not run shielders.

After Castorice has gained enough Newbud, she can summon Netherwing. While Netherwing is active, Castorice's Skill becomes Enhanced, becoming a fully AoE Joint ATK, much like Aglaea's Enhanced Basic. Castorice will consume 40% current HP from all allies (including herself, but excluding Netherwing) to deal 30% and 50% of her Max HP (80% total) to all enemies. This is absurdly powerful, and this isn't factoring in what Netherwing themselves can do.

Netherwing is quite the summon, being a fair bit different from the ones we've seen thus far. When Netherwing is summoned, their action is advanced by 100%. They bring with them a domain expansion — sorry, 'Territory' — that decreases all enemies' All-Type RES by up to 20% for simply being on field. Netherwing also inherits any existing DMG boosting stacks from Castorice's Talent.

They have an impressive initial SPD of 165 and a Max HP equal to 100% of the max value of Newbud (which we know is 34000 HP). After 3 of Netherwing's turns, or after their HP is reduced to 0, it disappears and dispels its Territory, Lost Netherland.

Netherwing is too large to fight in the same row as your team, so they occupy a sort of backup row when summoned. This also means enemies can't actually directly harm Netherwing. Netherwing has an emergency damage redirection passive, where allies cannot go below 1 HP, but all excess damage is redirected to Netherwing at 500% of the original value. Useful very often, but don't rely on this all the time since even Netherwing's absurd Max HP can't survive too long against 500% damage. Netherwing also boosts all allies DMG dealt by 10% for 3 turns when summoned.

That's just what Netherwing does passively. Now onto actual attacks. Netherwing can choose between a claw attack and a breath attack. The claw attack deals 40% of Castorice's Max HP to all enemies on the field. It's a rather powerful AoE attack that is used to end the action early or to preserve HP.

The breath attack, however... we’re not allowed to type the exact sentence we would use to describe this, so you know it's good. This is also a fully AoE attack that consumes 25% of Netherwing's Max HP to deal up to 24% Castorice's Max HP to all enemies. This does not end the action, by the way. You can just keep going, with the second cast dealing 28% Castorice's Max HP, and the third cast onward dealing 34%. This DMG Multiplier does not decrease until Netherwing disappears, so if you do not consume all of Netherwing's HP in one action, Netherwing's next breath attack will start off fully ramped up.

Consuming HP when Netherwing is at or below 25% Max HP will reduce their HP to 1 and trigger a finisher burst called Wings Sweep the Ruins. This is an enormous kamikaze Bounce attack, dealing 6 instances of Quantum DMG equal to 40% of Castorice's Max HP. This attack also restores 6% of Castorice's Max HP plus 800 to all allies. This attack can end up dealing a total of 240% of Castorice's Max HP if all the Bounces land on one enemy.

Combining this with a fully channelled breath attack, you're adding an extra 120% for a new total of 360% DMG multiplier. This is absurd, and getting to heal allies when Netherwing leaves is just the cherry on top.

There are two main ways to utilise Netherwing’s power. The first way is to just immediately use all 4 breath attacks in one action and go in for the big finisher explosion. This is the generally preferred way, especially after factoring in her A6 Bonus Trace. 

The second way is to hold off on finishing the breath attack, either by only doing 3 breath attacks into a claw, or by just skipping the breath attack and using Netherwing’s claw attack. This is useful if you need to stack buffs onto Netherwing after they are already summoned, or if you want to delay the explosion for some reason. This playstyle is imperative in Sunday teams.

This is all just at base without factoring in the Bonus Ability Traces.

Castorice's A2 allows for Newbud to be charged by factoring in ally healing received; 100% of the healed value is stored into Newbud. If Netherwing is on the field, the healing is instead converted into HP for Netherwing. The converted value for each ally cannot exceed 12% of Newbud's maximum value (so this only counts up to 4080 HP per ally), and the value can be taken from the ally again after any unit takes action. Oh, and overhealing is absolutely included in the conversion, so don’t worry about your healers’ efforts going to waste. This is the Trace we mentioned earlier when we said you definitely only want to use Abundance healers with Castorice. With someone like Gallagher or Luocha on the team, not only do you heavily offset the damage everyone is taking from Castorice's Skill uses, but you also greatly accelerate the accumulation of Newbud for fast resummons of Netherwing.

A4 will grant Castorice a 40% SPD boost as long as her current HP is greater or equal to 50%. In addition to this, when Netherwing deals fatal damage to all enemies on the field with their breath attack, or brings them to a point where they cannot lose more HP (such as a phase transition), Netherwing will gain 100% SPD for 1 turn.

This provides Castorice a very frequent potent SPD boost in combat, allowing her to fully benefit from the 4-piece bonus of the Poet of Mourning Collapse relic set while still getting to be fast. The bonus for Netherwing is for AoE content like Pure Fiction, where Netherwing's breath attack can wipe the field easily, and it lets them act almost instantly against the new incoming enemies.

Her A6 makes it so that each time Netherwing uses their breath attack, their DMG dealt will increase by 30%. This effect stacks up to 6 times and lasts until the end of the turn. Realistically, it is not possible to have Netherwing use their breath attack more than 4 times (since the cost would become exactly 100% Max HP), but certain Blessings or Eidolons could potentially increase this value.

Either way, with this Trace active, it now becomes more efficient to go all out on the breath attack if you choose to use it, as the ramping DMG boost will then also apply to Wings Sweep the Ruins, resulting in a colossal nuke against enemies.

Eidolons are, as usual, completely unnecessary, but should you choose to go for them, you won't be disappointed. E2 in particular is a huge damage increase on Netherwing's breath attack, allowing you to cast it a total of 6 times in succession, while advancing Castorice's action by 100% and granting a head start towards the next summon of Netherwing.

Please read the comparison between her Signature and her Eidolons if you would like help in deciding which to go for.

Castorice is a harbinger of death. She has no issues with decimating everything in front of her while also providing an accessible lifeline for the party. By being completely SP neutral, she also has no issue with other characters using Skill Points, especially for healers to be able to maximise their healing output.

We’ve already discussed healing, but when it comes to support, the best general pairing for Castorice is the Remembrance Trailblazer. Mem's Support is a fantastic boon to Castorice's already insane damage, as the undiluted multiplier from the True DMG lets you pretty much annihilate whatever's bold enough to be in front of you. Additionally, the inclusion of Mem in the team means Castorice has an extra target to siphon HP from, further increasing the generation of Newbud and accelerating the next use of her Ultimate, and the Trailblazer can contribute to the healing amount by using their Skill to heal Mem.

The True DMG multiplier isn't as high as it could be since Castorice doesn't meet the Energy requirement to do so (given that it's technically 0), but thanks to the Trailblazer's Bonus Trace, she still gets a total of 36% extra True DMG. Mem's Support is also automatically mirrored onto Netherwing when they are summoned, so there's no risk of losing value from the powerful buff. Mem also being able to directly attack helps to proc HP healing and draining effects from the team, and can even further accelerate the accumulation of Newbud.

Tribbie is probably the best general support for Castorice. Tribbie is fantastic for Castorice for the same reasons that Tribbie is great for Mydei; Tribbie's buffs are universal and are not tied to any one particular stat, meaning that the HP scaling Castorice will get full value at all times. Tribbie also ends up having wonderful synergy with the aforementioned Abundance healers since they require attacking to proc their healing.

Tribbie’s frequent follow-up attacks mean she can equally frequently proc Luocha’s or Gallagher’s healing effects, contributing even more to Newbud generation. You’re probably seeing a theme here by now. In addition to this, since Tribbie is a HP scaler herself, Castorice’s HP draining Skills will be able to generate a lot more Newbud upfront due to Tribbie’s build, resulting in her having a very high amount of Max HP.

These two characters of Tribbie and the Remembrance Trailblazer make up the best support team for Castorice. They provide the team with everything you could possibly want and then some more on top. It’s great that one of these characters is freely available to everyone, but Tribbie in particular provides the largest increase to overall performance, so it’s important to know this if you plan on having the strongest Castorice team possible.

Sunday is, of course, an alternative for Castorice, but is surprisingly more challenging to make use of for Castorice specifically. As Castorice doesn't use Energy, Sunday's Energy Restore is completely useless. Worse still is that Netherwing will not mirror Sunday's buffs if they were already active before Netherwing was summoned; Sunday would need to refresh the benefits of his Skill, Ultimate, and Talent directly in order for Netherwing to gain those benefits.

This is where the aforementioned second playstyle of Netherwing comes in. By delaying the use of Wings Sweep the Ruins by using Netherwing’s claw attack, you give Sunday enough time to re-buff Castorice and also have the effects spread to Netherwing, leading to a fully powered-up finisher.

Castorice also has fluctuating SPD values, especially when losing large amounts of HP at once, meaning that attempting to SPD tune to Sunday is quite the headache, and Netherwing's naturally very high SPD of 165 compounds this further. Giving Castorice more turns will also lead to steeper HP drain on the entire party, putting more pressure on the healers to be able to heal things back quickly enough — remember that Castorice's HP drain is based on current HP, so if everyone is already very low when she uses her Skill, the amount of Newbud she will generate will be significantly reduced, leading to far fewer Ultimate uses.

It's not impossible to use Sunday by any means, but it should be pretty clear that he’s definitely more challenging to use.

If you are interested in running a dual DPS setup, then the number 1 pick for that is the vanquisher Mydei. He already has no trouble fluctuating his own HP in order to deal damage, and has plenty of ways to regain it as well. Having a naturally nigh-unkillable unit on the team with the dragon that also prevents death can result in an extraordinarily durable team comp that deals huge damage as well.

Do note that if you use Mydei with her, you're somewhat forcing yourself to also use Tribbie as the support for both the DPS. Mydei would be taking the Remembrance Trailblazer's spot in the team, and this is again due to Tribbie providing universal buffs that benefit both Mydei and Castorice simultaneously. Neither of these two DPS explicitly needs the other to function, they work masterfully alone or together, but that choice is ultimately yours. Mydei is a good option to have in case the enemy is also weak to Imaginary.

If you are lacking Tribbie, this is going to result in a sizeable reduction to Castorice’s performance, and makes running dual DPS with Mydei extremely difficult, but it’s not completely over if you don’t have Tribbie… There is still the classic option of putting in Pela. The DEF Reduction she provides is greatly appreciated, and due to the extremely SP positive nature of the team (regardless of if you're using Remembrance Trailblazer or Mydei for the other slot), Pela has plenty of Skill Points to use to funnel herself enough Energy for maximum uptime on her Ultimate's debuff. Jiaoqiu is also quite similar so if he's not being used for a certain Self-Annihilator, he can also be used for Castorice. Finally, Ruan Mei can also be used as a Tribbie replacement if she’s not used elsewhere.

It's definitely far worse than using Tribbie, but at least you’re not completely and utterly out of options if you don’t have Tribbie.

Lastly, actually playing Castorice. The actual in-combat experience is not that complicated, to the point that even Auto-Battle will play exactly as you would prefer to play to maximise damage. The issue is more in building the team ahead of said battle.

Aside from that, there's not much else to say. She's crazy strong, and somehow has room to grow if units get released that are tailored for her gameplay. She's quite easy to pilot (if you're not using Sunday, sorry), and worst case scenario, Auto-Battle has you covered too. Strong in all game modes, beautiful design, and she's got a dragon.

Happy anniversary.