Mydei — Honkai Star Rail Character Guide

Overview

HP-scaling berserker who enters an autonomous Vendetta state, gaining massive HP increases and death immunity at the cost of manual control. Converts damage taken into Charge for devastating Blast nukes. ATK buffs are completely wasted on him.

HP-scaling Destruction DPS who builds Charge through HP loss, then enters an autonomous Vendetta state with 50% increased Max HP and DEF fixed at 0. During Vendetta, automatically uses Kingslayer Be King each turn and triggers Godslayer Be God as an extra turn when Charge hits 150. All damage scales entirely off Max HP — ATK is irrelevant. Manages a 160-Energy Ultimate cycle fueled by frequent enemy hits (guaranteed via Taunt) and Skill energy gain.

Key Mechanics

• All damage scales with Max HP — ATK buffs (Tingyun, Robin, Asta, Yukong) provide zero value. Seek DMG%, RES PEN, DEF Shred, CRIT, and Vulnerability amplification instead.
• Shields prevent Charge generation — damage absorbed by shields does not count as HP loss. Preservation sustains (Aventurine, Gepard, Fu Xuan, March 7th) directly sabotage Mydei's core mechanic. Use Abundance healers exclusively.
• Vendetta is fully autonomous except for Ultimate targeting. Kingslayer Be King targets are AI-chosen; Godslayer Be God targets the enemy marked by the most recent Ultimate. In target-sensitive encounters, frequent Ultimate usage is critical for directing damage.
• A6 Trace requires 8000+ Max HP (pre-combat) for full bonuses. Below this threshold, Mydei loses up to 48% CRIT Rate and 100% Charge gain — reaching 8000 HP is the single most important stat target.
• Godslayer Be God triggers as an extra turn (not an action advance), meaning it does not consume buff durations. This makes duration-based buffs from supports like Trailblazer Remembrance's True DMG buff persist through multiple GBG casts.

Best Teams for Mydei

Hypercarry

Mydei's core composition maximizing damage with dual amplifiers and a healer. Standard version uses Sunday + Tribbie for action advance and universal amplification. Chrysos Heir variant using Cyrene + Cerydra is significantly stronger when the roster supports 3+ Chrysos Heirs, but locked to specific 5-star members. Accessible to all players via the F2P version with Remembrance Trailblazer + Pela.

• S-tier: Mydei, Sunday, Tribbie, Luocha
• S-tier: Mydei, Sunday, Tribbie, Gallagher
• S-tier: Mydei, Cyrene, Cerydra, Hyacine
• A-tier: Mydei, Cyrene, Tribbie, Hyacine
• B-tier: Mydei, Trailblazer • Remembrance, Pela, Lynx

Dual DPS

Mydei paired alongside Castorice in a dual-threat composition. Mydei's constant HP consumption rapidly generates Newbud for Castorice's Ultimate while dealing sustained Blast damage. Tribbie buffs both DPS simultaneously. Sustain is essential since neither carry is fully self-sufficient in this setup.

• A-tier: Castorice, Mydei, Tribbie, Gallagher

Best Teammates

Amplifiers: Sunday (S+), Tribbie (S+), Cerydra (A), Cyrene (A), Trailblazer • Remembrance (B), Sparkle (B), Bronya (C), Pela (C), Jiaoqiu (C)

Sustains: Gallagher (A), Luocha (S+), Huohuo (B), Lingsha (B), Hyacine (A), Lynx (C)

Investment Priority

1. LC S1 — Signature provides 60% DMG boost to Skill and Ultimate when consuming HP, highest base HP stat, and a unique Charge acceleration mechanic. The power gap to F2P options is enormous — Mydei with and without this LC operate at different power levels.
2. E1 — Converts Godslayer Be God from Blast to full AoE, dealing primary target damage to all enemies. Transforms Pure Fiction viability from mediocre to excellent since 280% Max HP now hits all targets. Also adds 30% primary target bonus for boss damage.
3. E2 — 15% DEF ignore is a multiplicative damage increase in Vendetta. Healing-to-Charge conversion (40% of healed amount) significantly accelerates Godslayer Be God cycling with Gallagher or Luocha, enabling near-permanent nuke spam.

Best Relics

Recommended: scholar-lost-in-erudition with bone-collections-serene-demesne

Stat targets: HP 8000+, CRIT Rate 90-100% in-combat, CRIT DMG 160%+, SPD 134+ or base

Main stats: Body: HP% / CRIT DMG · Feet: SPD / HP% · Sphere: HP% / Imaginary DMG · Rope: HP%

Important Notes

• Forced auto-battle during Vendetta state — only manually controllable action is Ultimate, which marks the priority target for the next Godslayer Be God.
• ATK buffers (Tingyun, Yukong, Asta, Robin) provide zero value — Mydei deals damage entirely from Max HP, making all ATK buffs wasted stat.
• Break Effect buffers (Ruan Mei, Harmony Trailblazer) provide minimal value — Mydei does not scale with Break Effect and the stats are largely wasted.
• A6 Trace requires 8000+ Max HP for full 48% CRIT Rate bonus — prioritize HP% stats and HP-boosting gear until this threshold is reached.
• Auto-battle during Vendetta can cause issues in target-sensitive encounters like Pure Fiction add phases and Apocalyptic Shadow mechanics requiring specific targeting.