Mydei Build Guide 4.3 – Best Relics, Light Cones & Teams (HSR)

Mydei Build Guide 4.3 — Mydei is one of the most unique and powerful DPS characters in Honkai Star Rail. He burns his own HP to deal massive Imaginary damage and builds Charge to enter a powerful state called Vendetta. When played correctly, he hits incredibly hard, sustains himself, and becomes nearly impossible to kill. This guide covers everything you need to build him right in patch 4.3.

TL;DR – Quick Summary

• Mydei is a 5-star Imaginary Destruction DPS who converts HP loss into damage and Charge.
• Best Relic set: Scholar Lost in Erudition (4-piece).
• Best Planar Ornament: Bone Collection’s Serene Demesne.
• Best Light Cone: Flame of Blood, Blaze My Path (his signature).
• Best F2P Light Cone: Ninja Record: Sound Hunt or A Secret Vow.
• Stat goals: 8,000+ Max HP, 70%+ CRIT Rate, 140%+ CRIT DMG, 134+ SPD.
• Best teams pair him with Sunday, Tribbie, and a strong healer like Luocha.
• E1 is his strongest Eidolon — do not sleep on it.

Who Is Mydei in Honkai Star Rail?

Mydei, full name Mydeimos, is a 5-star Imaginary character following the Path of Destruction. He is the crown prince of Kremnos — a city consumed by mist, war, and a divine curse. His lore paints him as an undying warrior who must slay a god to become one. That energy carries directly into his gameplay.

He was released in Version 3.1 in March 2025 and immediately made an impact as a top-tier hypercarry. His core mechanic is simple: he sacrifices his own HP to deal damage and accumulate Charge. Once enough Charge builds up, he enters Vendetta state — which boosts his Max HP, gives him immunity to crowd control, and lets him auto-use powerful enhanced attacks. Even if he would normally die, he survives. He is simultaneously one of the tankiest and hardest-hitting characters in the game.

Check out his full character profile on our Mydei character page.

Mydei Kit Overview

Mydei’s kit revolves around one loop: lose HP, gain Charge, enter Vendetta, deal massive damage. Here is each ability explained clearly.

Basic ATK – Vow of Voyage

Deals single-target Imaginary DMG equal to 50% of Mydei’s Max HP. It also generates 20 Energy. You will rarely use this in endgame since the Skill auto-activates during Vendetta, but it is useful in early rotation for Energy generation.

Skill – Deaths are Legion, Regrets are None

Consumes 50% of Mydei’s current HP and deals blast Imaginary DMG — hitting one main target and adjacent enemies. The main target takes damage equal to 90% of Mydei’s Max HP. This is the HP drain that fuels his Charge. If he does not have enough HP, it reduces him to 1 HP instead of killing him. The Skill generates 30 Energy per use.

Enhanced Skill – Kingslayer Be King (Vendetta Only)

An upgraded version of the Skill that auto-activates at the start of each turn during Vendetta. Same HP-cost mechanic but hits harder. This keeps Charge building passively during Vendetta state.

Enhanced Skill – Godslayer Be God (150 Charge)

The big hit. Triggered automatically when Charge reaches 150 during Vendetta. Consumes Charge and deals enormous blast Imaginary DMG to one target and adjacent enemies — based on his Max HP. This is his peak damage moment and the main reason to stack Max HP.

Ultimate – Throne of Bones (160 Energy)

Restores HP equal to a percentage of Mydei’s Max HP, accumulates Charge, deals blast Imaginary DMG, and Taunts the target and adjacent enemies for 2 turns. It also ensures the next Godslayer Be God hits the taunted target. The Ultimate has a 160 Energy cost — one of the highest in the game — so Energy management matters.

Talent – Blood for Blood

This is the heart of his kit. For every 1% of HP Mydei loses, he gains 1 Charge (up to 200 total). When Charge hits 100, he spends 100 points to enter Vendetta. In Vendetta he restores HP, advances his action by 100%, gains bonus Max HP, drops his DEF to zero, and becomes immune to crowd control. When Charge hits 150 during Vendetta, he immediately takes an extra turn and auto-fires Godslayer Be God. If he takes a killing blow during Vendetta, he survives — Charge clears and he restores HP instead of dying.

Technique – Cage of Broken Lance

Pulls in nearby enemies and inflicts Daze before battle. When attacking Dazed enemies to start a fight, Mydei deals AoE Imaginary DMG to all enemies, Taunts them, and gains 30 Charge immediately. A great way to start his rotation ahead of schedule.

Major Traces

• A2 – Earth and Water: During Vendetta, Mydei cannot be knocked down by a killing blow — and this effect can trigger 3 times per battle. Incredible survivability.
• A4 – Thirty Tyrants: During Vendetta, Mydei is immune to all crowd control debuffs. He cannot be frozen, imprisoned, or stunned.
• A6 – Bloodied Chiton: When battle starts, if Mydei’s Max HP exceeds 4,000, every 100 extra HP increases his CRIT Rate by 1.2%, up to a cap of +48% at 8,000 Max HP. This is the core reason to stack Max HP — you can reach 70%+ CRIT Rate passively without relying on many substats.

Mydei Trace Priority

His most damaging abilities should be upgraded first. Here is the recommended order:

• 1st – Skill: Increases the DMG multiplier and HP consumption for Kingslayer Be King and Godslayer Be God.
• 2nd – Ultimate: Increases the HP restored, Charge gained, and DMG dealt by Throne of Bones.
• 3rd – Talent: Improves Vendetta HP restoration and Max HP bonus during the state.
• 4th – Basic ATK: Lowest priority. Leave this last.

Always unlock all Major Traces (A2, A4, A6) as a priority — especially A6, which gives massive free CRIT Rate based on Max HP.

Best Light Cones for Mydei (4.3)

1. Flame of Blood, Blaze My Path (Signature – Best Option)

Mydei’s own signature is clearly designed for him. It increases his Max HP and improves the healing he receives. Crucially, it also increases his DMG based on how much HP he has consumed — which he does constantly. It synergizes perfectly with every part of his kit and has no real competition for the top slot.

2. Ninja Record: Sound Hunt (Best F2P Option)

The current best free alternative. It provides a meaningful DMG bonus that scales well with Mydei’s rotation. Run this at Superimposition 5 for maximum benefit — it is available from the game’s store and does not require event luck.

3. A Secret Vow (4-Star Alternative)

When the wearer’s HP is equal to or lower than the target’s HP, it increases DMG dealt. Mydei frequently drains his own HP, which makes this condition easy to meet. A solid transitional pick if you do not have better options.

4. On the Fall of an Aeon (5-Star General Option)

From the Herta store. Increases ATK each time Mydei attacks, up to 4 stacks, and also boosts DMG when hitting weaknesses. A decent alternative if you already have it, but falls behind options focused on HP scaling.

5. Flames Afar (4-Star – Memory of Chaos Shop)

When Mydei’s HP loss in one hit exceeds 25% of Max HP — which happens every time he uses his Skill — it heals him for 15% Max HP and boosts his DMG by up to 50% for 2 turns. This can only trigger once every 3 turns, but it is a great budget option especially for newer players. Buy it with MoC currency.

Best Relics for Mydei (4.3)

Best Relic Set: Scholar Lost in Erudition (4-Piece)

This is the clear best-in-slot relic set for Mydei right now. The 2-piece bonus gives +8% CRIT Rate. The 4-piece bonus increases DMG dealt by his Skill and Ultimate by 20%, and after using the Ultimate, his next Skill usage deals 25% more DMG. Since Mydei’s entire damage output runs through his Skill and Ultimate, this set boosts his two biggest hits by a massive margin. Nothing else comes close.

Alternative: Longevous Disciple (4-Piece)

The 2-piece gives +12% Max HP and the 4-piece grants CRIT Rate whenever Mydei is hit or loses HP. Since he is constantly burning HP, this triggers reliably. It is a solid second choice if your Scholar pieces have terrible substats, but Scholar is still clearly superior once properly farmed.

2-Piece Mix Option

If neither set is well-rolled, you can combine 2-piece Scholar (CRIT Rate) and 2-piece Longevous Disciple (Max HP) for a balanced mix. Not as good as a full 4-piece Scholar but workable while you farm.

Best Planar Ornaments for Mydei (4.3)

Best: Bone Collection’s Serene Demesne

The top pick. The 2-piece bonus increases Max HP by 12%. If Mydei’s Max HP reaches 5,000 or higher — which is always the case once properly built — it also increases his and any memosprite’s CRIT DMG by 28%. More Max HP means more free CRIT Rate from A6, and then this set adds CRIT DMG on top. Perfect synergy from start to finish.

Alternative: Rutilant Arena

If Mydei’s CRIT Rate reaches 70% or above, this set gives +8% CRIT Rate and increases Skill and Basic ATK DMG by 20%. The condition is achievable with a well-built Mydei thanks to his A6 passive. Use this if you do not have good Bone Collection pieces yet.

Relic Main Stats and Substats for Mydei

Here is exactly what to look for on each relic slot:

• Head: HP (fixed)
• Hands: ATK (fixed)
• Body: CRIT DMG% (prioritize this)
• Feet: SPD or HP%
• Planar Sphere: Imaginary DMG%
• Link Rope: HP%

Substat priority: HP% → CRIT DMG% → CRIT Rate% → SPD → ATK%

Mydei’s A6 Trace does most of the CRIT Rate work automatically once you hit 8,000 Max HP. So your substat focus is CRIT DMG first, HP second. Aim for these endgame stat targets: 8,000+ Max HP, 70%+ CRIT Rate, 140%+ CRIT DMG, and 134+ SPD.

Best Teams for Mydei (4.3)

Mydei is a hypercarry. He does the damage — you just need to support him properly. He is flexible enough to work in several compositions.

Hypercarry Team (Best Option)

Run Mydei alongside Sunday, Tribbie, and Luocha. Sunday provides action advance and Crit DMG buffs that directly amplify Mydei’s big Godslayer hits. Tribbie adds more universal buffs and RES PEN. Luocha heals with high multipliers and his passive emergency healing is perfect — Mydei drains HP constantly and needs reliable recovery between Vendetta cycles. This is the highest-performing lineup available in 4.3.

Remembrance Support Team

Pair Mydei with Trailblazer (Remembrance), Sunday, and Lingsha. Remembrance Trailblazer provides CRIT DMG, CRIT Rate, and action speed via their Mem. Sunday adds CRIT DMG and action advance. Lingsha deals personal damage and can emergency-heal Mydei when his HP drops dangerously low after a Skill use.

Bronya/Sparkle Alternative Team

If you do not have Sunday, Bronya or Sparkle can substitute. Both provide action advance and team buffs. Bronya gives ATK and DMG buffs, while Sparkle adds CRIT DMG and Skill Point management. Add Huohuo for Energy regeneration and healing support.

Budget Team (F2P Friendly)

Mydei, Tingyun, Pela, and Natasha. Tingyun boosts ATK and helps Mydei reach his Ultimate faster. Pela debuffs enemies and reduces their DEF. Natasha keeps Mydei alive on a budget. This will not push the same numbers as the premium lineup, but it is a solid way to clear story content and lower-difficulty endgame modes.

Mydei Eidolons – Are They Worth It?

Mydei is a fully functional DPS at E0. His Eidolons are strong but not mandatory for most players.

• E1 – Frost Homes Spine of Steel (Best Value): Increases the Godslayer Be God damage multiplier on the main target by 30%. It also turns Godslayer Be God into a full AoE attack, hitting all enemies instead of just the main target and adjacent ones. This is a huge upgrade — especially in multi-enemy content. E1 is considered his most cost-effective Eidolon and is well worth chasing.
• E2: During Vendetta, Mydei ignores 15% of enemy DEF when dealing damage. Very strong and multiplicative with existing buffs, but comes at high investment cost.
• E4: Increases Mydei’s Max HP after entering Vendetta, which scales all his HP-based damage even higher. A good damage boost but not a game-changer on its own.
• E6: Pushes his damage ceiling significantly further but requires six copies — an extreme investment for most players.

For the majority of players, E0 for clear story and most endgame, or E1 for a meaningful upgrade, is the right stopping point.

Mydei Rotation and Gameplay Tips

His gameplay loop is mostly automatic once you understand it, but a few habits help a lot:

• Use the Technique before battle to pull enemies, deal AoE damage, and gain 30 Charge instantly. This jumpstarts his Vendetta cycle much faster.
• In battle, use the Skill to drain HP and build Charge. At 100 Charge, Vendetta activates automatically — no input needed.
• During Vendetta, Kingslayer Be King fires automatically at the start of each turn. At 150 Charge, Godslayer Be God fires automatically and gives Mydei an extra turn.
• Use the Ultimate as soon as possible. It restores HP, accumulates Charge, and sets up the next Godslayer hit. With 160 Energy cost, you need Energy support from teammates or Light Cones like Flames Afar or his signature.
• During Vendetta, Mydei’s DEF drops to zero. Do not panic — his A2 Trace lets him survive killing blows up to 3 times per battle. Trust the kit.
• Prioritize healers with high raw healing output, not just shields. Mydei needs actual HP recovery to fuel his next Charge cycle, not just damage mitigation.

How to Get Mydei

Mydei is a limited 5-star character. He debuted in Version 3.1 in March 2025. He is not available on the standard banner and can only be obtained during his limited Warp banner runs using Star Rail Special Passes. Check the official HoYoLAB announcement page for his next rerun schedule. His signature Light Cone, Flame of Blood, Blaze My Path, also only appears on the Light Cone Event Warp during his banner.

Mydei Ascension and Trace Materials

Here is everything you need to fully level and unlock all of Mydei’s Traces:

• Ascension Materials: Fear-Stomped Flesh / Courage-Torn Chest / Glory-Aspersed Torso (enemy drops from Amphoreus) and Harbinger of Strife (boss drop from Stagnant Shadow: Abyss of Fate in Janusopolis).
• Trace Materials: Borisin Teeth series (from Calyx Crimson: Bud of Destruction in Scalegorge Waterscape) and Auspice Sliver from the Echo of War: Inner Beast’s Battlefield weekly boss on Xianzhou Luofu.
• Special Material: Tracks of Destiny for his major Trace nodes — obtainable from Simulated Universe point rewards, the Nameless Honor Battle Pass, and seasonal events.

Start farming Borisin Teeth and Auspice Sliver early. Many of his materials are shared with other Destruction characters like Firefly and Yunli, so plan accordingly if you are building multiple DPS units.

Is Mydei Worth Pulling in Patch 4.3?

Absolutely. Mydei is one of the best single-target DPS characters in the game. He is self-sustaining, extremely durable, and hits harder than most when properly invested. His Vendetta mechanic gives him built-in survivability that most DPS characters simply do not have — and that translates to fewer healer restrictions in team building.

In patch 4.3, he remains competitive in Memory of Chaos and Apocalyptic Shadow. His main weakness is reliance on a strong healer and a 160 Energy Ultimate cost, but both of those are manageable with the right team. If you already have or plan to build characters like Sunday, Tribbie, or Luocha, Mydei slots right in and rewards the investment heavily.

Looking for more top DPS builds? Check out our guides for Castorice, Phainon, Firefly, and Blade. For support options that pair well with Mydei, see Sunday and Aventurine.

Mydei Build 4.3 – FAQ