Mydei is an Imaginary-element character who follows the Path of Destruction. His attacks scale with his Max HP, and he has the ability to survive fatal blows. His gameplay revolves around accumulating charge by losing HP and taking hits, which activates his Vendetta state. While in Vendetta, Mydei’s skills are enhanced, and his survivability increases significantly. He can be built as a hypercarry focused on high damage output or flexed into a variety of team compositions, making him a valuable addition to any player’s roster.
Best Cavern Relics
(2) Increases CRIT Rate by 8%.
(4) Increases DMG dealt by Skill and Ultimate by 20%. After using Ultimate, additionally increases the DMG dealt by the next Skill by 25%.
The bulk of Mydei’s damage comes primarily from his Skill and Enhanced Skill. This set provides the best damage boost for both his Skill damage and Ultimate damage.
(2) Increases Max HP by 12%.
(4) When the wearer is hit or has their HP consumed by an ally or themselves, their CRIT Rate increases by 8% for 2 turn(s) and up to 2 stacks.
This set specifically focuses on boosting Mydei’s HP, and since he consumes HP to use his Skill, it can also provide him with a Crit Rate bonus. However, its overall damage output falls short compared to what The Scholar Lost in Erudition set offers.
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(2) Increases the wearer's Max HP by 12%. When the wearer's Max HP is 5000 or higher, increases the wearer's and their memosprite's CRIT DMG by 28%.
Equipping this set on Mydei will undoubtedly enhance both his damage and durability.
(2) Increases the wearer's CRIT Rate by 8%. When the wearer's current CRIT Rate reaches 70% or higher, the wearer's Basic ATK and Skill DMG increase by 20%.
Meeting this set effect’s condition grants Mydei an extra boost to his Skill damage. However, he doesn’t benefit much from the Basic Attack bonus, since he rarely uses Basic Attacks.
Best Stats

Body
CRIT DMG

Boots
SPD

Sphere
Imaginary DMG Boost

Rope
HP%
Substats
HP% / CRIT DMG / SPD / CRIT Rate
info
Mydei’s main stat priority is HP%, as his damage and survivability scale with it. Next, focus on Crit Rate and Crit Damage to boost his output, aiming for a 1:2 ratio. Speed is also valuable to maintain his Vendetta uptime, with 120–135 being ideal. Imaginary Damage% and Effect RES are good secondary options for more damage or durability.
Best Light Cones
SourceLight Cone Event Warp
Vista
Increases the wearer's Max HP by 18~30% and Incoming Healing by 20~40%. When using Skill or Ultimate, consumes HP equal to 6.0~8.0% of the wearer's Max HP and increases the DMG dealt by this attack by 30~50%. If this effect's consumed HP is greater than 500, the DMG additionally increases by 30~50%.
If the current HP is not sufficient, this effect reduces the wearer's current HP down to 1.This Light Cone is his signature and greatly boosts both his damage and durability. It also provides extra damage whenever the HP consumed by his Skill exceeds 500.
SourceStellar Convergence, Light Cone Event Warp
Unfulfilled Yearning
Increases the wearer's CRIT rate by 18~30% and increases their Max HP by 18~30%. When the wearer is attacked or consumes their own HP, their DMG increases by 24~40%. This effect is removed after the wearer uses an attack.The Unreachable Side boosts Mydei’s Crit Rate and Max HP, increasing both his damage and durability. It also grants extra damage against enemies below 50% HP, helping him finish them off quickly.
SourceEvent, Herta's Store
Curtains Up!
Increases the wearer's Max HP by 12~24%. When losing or restoring this unit's HP, increases CRIT DMG by 18~36%, lasting for 2 turn(s). This effect can only trigger once per turn.This Light Cone’s effect suits Mydei well, as he consumes HP instead of a Skill Point to use his Skill. When he does, he gains Crit Damage that is immediately applied when the Skill is unleashed.
Massacre
Increases the wearer's CRIT Rate by 12~20%. The Skill DMG and Ultimate DMG dealt by the wearer increases by 24~40%.Mydei benefits from this Light Cone as it primarily boosts his Skill and Ultimate damage.
SourceStellar Warp, Departure Warp, Character Event Warp, Light Cone Event Warp
Spare No Effort
Increases DMG dealt by the wearer by 20~40%. The wearer also deals an extra 20~40% of DMG to enemies whose current HP percentage is equal to or higher than the wearer's current HP percentage.This is also a good option for Mydei, as it boosts his overall damage and grants additional damage when he targets enemies with equal or higher HP than his own.