Guide
How the kit works
Start with Basic Attack: Swift Edge, a sequence of up to four Wind attacks. The fourth hit gives 20 Flow when it connects. Time the first three attacks just before an enemy strike to dodge it and automatically launch Basic Attack: Raging Whirlwind. Timing the fourth attack instead gives it the same DMG and Daze multipliers as Raging Whirlwind, plus 15 Flow.
Raging Whirlwind gives 15 Flow on activation and another 20 when it hits. Hold during it to go straight into Basic Attack: Azure Wind's Shadowhunt. Otherwise, hold the Basic Attack input once you have 100 Flow to spend it on Shadowhunt. Its backward dodge can avoid an attack, trigger Vital View and give 15 Flow.
Each Perfect Dodge also grants Windborne, which lets Severian switch in with Entry Skill: Clear Out. Chain Attack: Coldblade Reap gives 35 Flow, while Ultimate: Annihilating Windstorm gives 100. A Dash Attack, Dodge Counter or Dodge: Spontaneity used during the basic combo does not reset its count.
Build and why
Use four pieces of Dawn's Bloom and two of Puffer Electro. Dawn's Bloom increases Basic Attack DMG, with another 20% for 25 seconds after Severian uses an EX Special Attack or Ultimate. Puffer Electro adds 8% PEN Ratio. Four pieces of Woodpecker Electro are an alternative: its CRIT Rate and ATK bonuses suit his kit.
On disc 4, choose CRIT Rate or CRIT DMG. On disc 5, use PEN Ratio or Wind DMG Bonus, and on disc 6 use Percent ATK. Look for CRIT Rate, CRIT DMG and Percent ATK in substats, in that order. CRIT Rate also feeds Additional Ability: Optimal Setup: each 1% grants 8.5 ATK, up to 100% CRIT Rate, when its team condition is met.
Incarcerating Grip is the first weapon choice. It gives 20% CRIT Rate, and a Basic Attack hit grants 10% ATK and ignores 15% Wind RES for 16 seconds. Sol Exuvia is next for its 20% CRIT Rate; its Eclipse effect ignores Ether RES, which does not improve Severian's Wind damage. The Brimstone follows, building ATK stacks from Basic Attacks, Dash Attacks or Dodge Counters.
Leveling priority
Follow the game's order: Core Passive first, then Basic Attack, Chain Attack, Special Attack, Assist and Dodge. The passive improves his damage and defines his dodge and Flow mechanics. Basic Attack comes next because his main Flow-spending attack belongs to that category; Chain Attack includes his Ultimate.
For maximum ascension, you need 800,000 Denny, 4 Basic Attack Certification Seal, 32 Advanced Attack Certification Seal and 30 Pioneer's Certification Seal.
For all skills, you need 2,905,000 Denny, 25 Basic Windbite Chip, 75 Advanced Windbite Chip, 250 Specialized Windbite Chip, 5 Hamster Cage Pass, 9 Timeworn Husk and 60 Higher Dimensional Data: Imitation Core.
Mindscapes worth it
Reins of Reason is worth considering for a major Flow boost: entering the battlefield gives Severian 150 Flow. A Perfect Dodge or Basic Attack: Azure Wind's Shadowhunt also grants 20% PEN Ratio for 25 seconds.
Double Espresso is another useful step. His attacks ignore 15% Wind RES, his Chain Attack gains 50 Flow instead of 35, and Shadowhunt grants Windborne. His Entry Skill can also be replaced by a Chain Attack once every 60 seconds.
Beneath a Little Star raises the Flow cap to 180 and increases the additional multiplier on Shadowhunt's final hit by a fixed 350%. The final hit also grants 5 Flow per second for 5 seconds. If you are choosing where to stop, The Last Light and A Heart Above 0°C only add skill levels, while Between Light and Shadow offers ATK and Decibel Generation Rate rather than a new Flow mechanic.
Common mistakes
Do not ignore enemy timing and simply repeat the full basic combo. A well-timed hit can dodge an attack and lead into Basic Attack: Raging Whirlwind, while a successful fourth-hit dodge strengthens that hit. Shadowflash helps when you miss a dodge, but its stacks are limited.
Do not sit at the 150 Flow cap while waiting for a perfect opening. Spend 100 when you have a safe chance, then build toward the next use. Also check your team before relying on the CRIT Rate to ATK conversion: it needs a Support, Stun or same-faction teammate.
Do not pick Sol Exuvia expecting its Ether RES effect to increase Wind damage. Its CRIT Rate is the relevant part of the weapon for Severian.