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Cornerstone profile was last updated on 08/October/2026.
To learn more about Cornerstone check the sections below. Use the tabs to quickly switch to the kind of information you're looking for.
Profile
Self-counter, enters [Delivery Process] status for 1 round.
Delivery Process:
While active, [Eligibility Assessment] DMG reduction is increased, capped at (Cornerstone's ATK at battle start * 160%). After the enemy's round ends, Cornerstone releases [Delivery Feedback] to attack. [Inspection Process] does not trigger this round. Not affected by [Control] on release. Stacks duration when re-obtained, cannot be dispelled.
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[Attack]
1-target attack. Deals 200% Reality DMG. If in [Inspection Process] status, this attack additionally deals 200% Reality DMG and Critical DMG +40%. This attack counts as 1 riposte.
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[Attack]
1-target attack. Deals 300% Reality DMG. If in [Inspection Process] status, this attack additionally deals 200% Reality DMG and Critical DMG +60%. This attack counts as 1 riposte.
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[Attack]
1-target attack. Deals 500% Reality DMG. If in [Inspection Process] status, this attack additionally deals 200% Reality DMG and Critical DMG +100%. This attack counts as 1 riposte.
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[Counter]
Self-counter. Enters [Inspection Process] status for 2 rounds. Grants self 2 stacks of [Progressive Iteration] for 2 rounds.
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[Counter]
Self-counter. Enters [Inspection Process] status for 2 rounds. Grants self 3 stacks of [Progressive Iteration] for 2 rounds.
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[Counter]
Self-counter. Enters [Inspection Process] status for 2 rounds. Grants self 5 stacks of [Progressive Iteration] for 2 rounds.
Inspection Process:
After the enemy's round ends, Cornerstone releases [Inspection Feedback] to attack. Not affected by [Control] on release. Stacks duration when re-obtained, cannot be dispelled.
Inspection Feedback:
Mass attack. Deals 1000% Reality DMG to all enemies. Grants self 1 stack of [Design Revision], increases self Moxie by +1. Clears all [Trial and Error], and for every 1000 cleared, this attack additionally deals 100% Reality DMG. This attack counts as 1 riposte.
Progressive Iteration:
Riposte DMG Bonus +4%, Incantation Might +4% (stackable, up to 20 stacks; each stack has independent duration; cannot be dispelled).
While Cornerstone is on the field, all allies gain [Eligibility Assessment]. Cornerstone gains [Trial and Error]. Cornerstone's Max Moxie -1, and the Ultimate's Moxie Cost -1.
Every time an ally takes an extra action, Cornerstone grants self 1 stack of [Progressive Iteration] for 2 rounds. If it is a Riposte, grants 1 additional stack. For every 10 stacks of [Progressive Iteration] gained, Cornerstone grants self 1 stack of [Design Revision].
When entering battle, increases ATK by +5%.
Own Ultimate does not count toward the ally Spelldock limit. When entering battle, Cornerstone increases self Moxie by +2.
Overflowing Moxie is temporarily stored. At the end of the round, if self Moxie has remaining capacity, it is replenished (up to a maximum of 4 stored Moxie).
Eligibility Assessment:
When attacked, reduces DMG taken. Reduction capped at (Cornerstone's ATK at battle start * 80%). The reduced DMG amount is stored by Cornerstone as [Trial and Error].
Trial and Error:
Cap is (Cornerstone's ATK at battle start * 500%). When other allies execute a Riposte, adds Reality DMG equal to (Cornerstone's ATK * 100%), and increases that additional Reality DMG by 100% based on the current [Trial and Error] percentage. Additional DMG is dealt by Cornerstone. [Trial and Error] stops storing once capped, but [Eligibility Assessment] still reduces DMG.
Progressive Iteration:
Riposte DMG Bonus +4%, Incantation Might +4% (stackable, up to 20 stacks; each stack has independent duration; cannot be dispelled).
Design Revision:
Can be consumed by [Delivery Feedback] triggered by the Ultimate to enhance its effects (stackable up to 10 stacks; cannot be dispelled).
Cornerstone doesn't have an Euphoria update yet. If it will be released, we will add it here.
Lv. 1:
[As Things Are]: Reduces the number of [Progressive Iteration] stacks required to gain 1 stack of [Design Revision] to 8.
[Inspection Feedback]: [Delivery Feedback] Reality DMG increased to 4000%, and the condition to consume [Design Revision] reduced to 4.
[Figure-Ground Relationship]: [Inspection Feedback] Reality DMG increased to 2500%.
Lv. 2:
[Inspection Feedback]: [Delivery Feedback] additional Reality DMG dealt by consuming [Design Revision] increased to 2500%, Ultimate Might increased to 100%, Penetration Rate increased to 30%.
[Figure-Ground Relationship]: [Inspection Feedback] for every 1000 [Trial and Error] cleared, this attack additionally deals 250% Reality DMG, and [Design Revision] granted to self increased to 2 stacks.
[As Things Are]: Riposte DMG Bonus and Incantation Might per stack of [Progressive Iteration] increased to 5%.
Lv. 3:
[As Things Are]: [Trial and Error] Reality DMG added when other allies execute a riposte increased to Cornerstone's ATK * 200%, and the additional DMG increase based on current [Trial and Error] percentage of cap increased to 250%.
Lv. 4:
[As Things Are]: [Eligibility Assessment] DMG reduction effect increased to Cornerstone's ATK at battle start * 120%. [Trial and Error] storage cap increased to Cornerstone's ATK at battle start * 600%.
[Inspection Feedback]: During [Delivery Process], [Eligibility Assessment] DMG reduction effect increased to ATK at battle start * 240%.
Lv. 5:
[Inspection Feedback]: [Delivery Feedback] Reality DMG increased to 5000%. For every 1000 [Trial and Error] cleared, additional Reality DMG dealt increased to 250%.
[As Things Are]: Riposte DMG Bonus and Incantation Might per stack of [Progressive Iteration] increased to 6%, stack cap increased to 25.
Review
Cornerstone is a 6* Mineral DPS unit. She is a Riposte unit that specializes in absorbing incoming damage, using it to empower allied Riposte attacks, and then firing it back onto the opposition at the end of the round.
Long story short, Cornerstone is an Extra Action unit cosplaying as a Riposte unit. Her kit kind of “solves” the issue of Riposte in that she is not reliant on enemies hitting her to trigger her attack. Rather, she relies on the team getting hit and then uses the received damage to empower her personal damage and the team’s Riposte damage.
The cornerstone (heh) of Cornerstone’s gameplay is her [Delivery Feedback] attack, which is a Riposte attack tied to her Ultimate. Her kit is all about facilitating both the max damage she can deal with the attack and the frequency at which she can unleash said attack, so let’s break it down:
First, her Precognition allows her to mitigate (and sometimes even negate) incoming damage, and this mitigated damage is stored via her [Trial and Error] up to a cap. This status does two things:
Whenever an ally performs a Riposte, she adds an additional on-hit damage rider equivalent to the current [Trial and Error] value. This counts as an extra instance of damage attributed to Cornerstone.
Whenever she performs her Riposte attacks, she clears all [Trial and Error] values to increase her damage. This means that she’ll need to re-gather [Trial and Error] once more the following round.
Second, she needs to gather [Progressive Iteration] stacks and [Design Revision] stacks. The former gives her Incantation Might and Riposte Damage bonus, while the latter increases the multipliers, PEN, and Ultimate Might of [Delivery Feedback].
She gains [Design Revision] for every 10 [Progressive Iteration] stacks gathered or when she performs her own Counter or Ultimate, and she gains a stack of [Progressive Iteration] every time the team performs an extra action, doubled if the action is a Riposte. In short, you want the team to be performing as many extra actions as possible, preferably Ripostes.
Both of her cards help with this stacking: her Skill 1, [Concrete Functionality] is a run of the mill attack that counts as a Riposte meaning it grants her 2 stacks of [Progressive Iteration], while her Skill 2, [Figure-Ground Relationship], grants her [Progressive Iteration] stacks while allowing her to perform a weaker Riposte attack at the end of the round for another 2 stacks.
Finally, her Precognition and Insight passives facilitate her Moxie gain: she only has 4 Moxie and only requires 4 to cast her Ult, she gains 2 Moxie at the start of the battle, and Ultimate does not take spelldock space, and she has a personal Moxie Storage system. This means you should be casting Cornerstone’s ultimate every round through a combination of tuning, card merging, and storing excess Moxie.
Her kit might seem complicated but the gameplay loop is relatively simple:
Maintain Cornerstone’s Counter status at all times and gather her Moxie as fast as possible;
Upon casting her ult, merge her cards at least once, then cast one of her cards. Combined with her own Counter and Ultimate attack giving her Moxie, you are refunding 4 Moxie post Ultimate, letting you cast her Ultimate every round.
Unfinished Tune helps massively in this regard as it lets you force Cornerstone’s cards.
As with most 6* units in Reverse: 1999, Cornerstone is already complete at P0. That said, there are a few portrait breakpoints that you can aim for if you do decide to go for them:
Portrait 1 doubles the damage of both [Delivery Feedback] and [Inspection Feedback] whilst increasing the efficiency of gathering and consuming [Design Revision]. Portrait 2 is another further damage personal damage increase and scaling increase, and is the most efficient stopping point.
Because of the nature of her kit, Cornerstone’s teambuilding is rather flexible when it comes to teammates. However, there are a few standout units that work exceptionally well with her:
One of her best partners is 
J with his Euphoria 1. He and Cornerstone work perfectly together as he can perform multiple Ripostes per turn to provide Cornerstone her needed stacks while also applying her damage riders, he provides a ton of offensive buffs, all the while acting as the team’s sustain and sub-DPS.
Rhiannon provides hefty offensive utility that anyone can benefit from. Additionally, Rhiannon being completely AP-free helps with facilitating Cornerstone’s rotation. It’s important to note that Rhiannon’s [Sensory Bond] has a bit of anti-synergy with Cornerstone since it prevents enemies from attacking, but it’s a small price to pay in exchange for her powerful offensive utility.
Since Cornerstone is an extra action unit, 
Flutterpage is a no-brainer. She massively buffs all of Cornerstone’s damage (including even her Skill 1 due to it counting as a Riposte), provides +1AP, and ensures that all of Cornerstone’s attacks will always be critical hits.
There’s a unique synergy between Cornerstone and 
Anjo Nala . When bound to Anjo, Cornerstone easily stacks Anjo’s [Legato Harmony] due to her Skill 1 counting as a Riposte.
The Ritual wheelchair of 
Moldir with her Euphoria 1 and 
Narcissus proves to be a good team for Cornerstone due to their hefty Ultimate related buffs and frequent extra actions. Moldir in particular can perform Ripostes, which is a huge bonus for Cornerstone.
Good baseline damage that scales well against enemies that hit hard;
Makes all Riposte attacks stronger via her [Trial and Error] damage riders;
Provides damage mitigation, even negation, that can be useful in high pressure scenarios;
Flexible teambuilding, able to slot in with Extra Action supports or Ritual supports.
Damage ceiling is heavily reliant on enemies hitting hard, meaning damage output dramatically drops if enemies refuse to attack;
Reliant on allies performing Extra Actions, preferably Ripostes, to reach her full damage potential.
Requires some micromanagement to reach her full potential.
Stats and Build
Crit Focused Resonance, best used when ran with Flutterpage.
Attack Focused Resonance, higher damage mitigation threshold, good general choice if not ran with Flutterpage.
Where Light and Shadow Rest - 
Cornerstone’s signature chube and is also her best in slot. It gives her all the stats she needs, specially Crit related stats and a unique Riposte damage stat. The only caveat here is she needs to be ran with an ally that can consistently perform multiple Ripostes.
The Final Roll - 
Recoleta’s signature chube. This is a very good option that gives identical stats as her signature chube, except it gives Ultimate Might rather than Riposte Damage bonus. The upside of running this chube is that you’re not reliant on Ripostes to fully stack the Critical Damage buff.
On the Hand of Time - Flutterpage’s signature chube. A good generic option for any Extra Action DPS. It gives Cornerstone a decent amount of Critical Damage, especially if you use her Skill 1 during the round.
Outside the City - 
Jiu Niangzi’s signature chube. This has the potential to give tons of Crit-related stats and is powerful when paired with Flutterpage. However, it takes a long time to stack and requires Cornerstone spamming her Skill 1 (as it’s the only that can activate the chube conditions), and thus should only be considered in long fights.
Cornerstone stats aren't available yet. They will be added soon!
Synergy & Teams
The teams below come from our Teams database and showcase ANY team with Cornerstone present within in all content available in the game.
Add One More Schwing
Niche 1: Riposte || Niche 2: -
A Riposte team helmed by Cornerstone. The fourth slot is flexible, usually either Rhiannon or Lopera. J uses Euphoria 1.
If you're looking for more team information, check our Team Tier List:
Cornerstone Synergy information aren't available yet. They will be added soon!
Lore
Cornerstone Lore information aren't available yet. They will be added soon!
