Theorylytics

Firefly vs Mydei

Firefly vs Mydei — two Destruction characters competing for the same roster slot.

TL;DR — Quick Pick

Pick Firefly if…

  • You need a Fire Destruction unit and Firefly's kit matches your account gap.
  • You prefer Break DPS gameplay over Mydei's Main DPS identity.
  • Yes for Super Break—Firefly remains a top Fire Break carry.

Pick Mydei if…

  • You need a Imaginary Destruction unit and Mydei's kit matches your account gap.
  • You prefer Main DPS gameplay over Firefly's Break DPS identity.
  • Yes—Mydei is a strong Imaginary HP-drain Destruction carry.
Verdict

Firefly and Mydei are both Destruction investments that answer different account needs. Firefly (Fire, Break DPS) shines when Yes for Super Break—Firefly remains a top Fire Break carry.. Mydei (Imaginary, Main DPS) is the better commit when Yes—Mydei is a strong Imaginary HP-drain Destruction carry.. Compare signature builds, team requirements, and your existing supports before pulling either.

At a Glance

Firefly
Stat
Mydei
Fire
Element
Imaginary
Destruction
Path
Destruction
5★
Rarity
5★
Break DPS
Primary role
Main DPS
MoC: S · PF: A · AS: SWinner
Endgame ratings
MoC: A · PF: A · AS: B
CRIT Rate ≥ CRIT DMG
Scaling focus
CRIT Rate ≥ CRIT DMG
Fire + Destruction
Playstyle
Imaginary + Destruction
Moderate
Team flexibility
Moderate
Fugue / The Dahlia / Lingsha
Best support shell
Sunday / Tribbie / Luocha
On the Fall of an Aeon — Accessible Destruction cone—superimpose when possible.
F2P Light Cone
On the Fall of an Aeon — Accessible Destruction cone—superimpose when possible.
Excellent
E0 viability
Excellent

Strengths & Weaknesses

Firefly

Strengths
  • Ultimate “Fyrefly Type-IV: Complete Combustion” enters Complete Combustion with full action advance, SPD, and Break-boosted Enhanced attacks—most of the kit’s damage lives inside that window, not on filler Basics.
  • Skill “Order: Aerial Bombardment” spends a large HP chunk to refund Energy and advance action—the rotation wants controlled self-damage, not panic healing that cancels the state.
  • Talent “Chrysalid Pyronexus” scales DMG Reduction with low HP and locks max reduction in the burst state—survivability is written into the damage plan, not bolted on later.
Weaknesses
  • E0 without “Whereabouts Should Dreams Rest” is still clearable, but the gap versus a signature copy is larger than a single eidolon for most Destruction carries—plan the cone before deep eidolon hunting.
  • HP-spend skills mean Firefly can soft-lock if sustain is weak or if a healer tops them up at the wrong time and breaks a low-HP / Charge condition.
  • Firefly wants Break Effect supports and Toughness bars that can actually be broken; into awkward weakness line-ups the Complete Combustion / Break loop loses most of its damage.

Mydei

Strengths
  • Ultimate “Throne of Bones” Blast-hits the main target plus adjacent enemies—most of the kit’s damage lives inside that window, not on filler Basics.
  • Skill “Deaths are Legion, Regrets are None” spends HP as a deliberate self-damage cost—the rotation wants controlled self-damage, not panic healing that cancels the state.
  • “Blood for Blood” spends HP as a deliberate self-damage cost—cleaving a trash mob can snowball into another full Skill/Ult cycle.
Weaknesses
  • E0 without “A Thankless Coronation” is still clearable, but the gap versus a signature copy is larger than a single eidolon for most Destruction carries—plan the cone before deep eidolon hunting.
  • HP-spend skills mean Mydei can soft-lock if sustain is weak or if a healer tops them up at the wrong time and breaks a low-HP / Charge condition.
  • Extra-turn and single-target Ultimate patterns shine on bosses but stall in Pure Fiction unless adds die fast enough to proc the talent loop.

Shared Team Members

With Firefly

Tingyun amps Break Effect / action value so Toughness bars die on schedule.

With Mydei

Tingyun is the Advance / DMG amp — time their Skill/Ult for the carry’s damage window.

With Firefly

Pela enables Super Break / Toughness pressure rather than a generic CRIT Harmony slot.

With Mydei

Pela applies DEF shred / vulnerability so the carry’s multipliers actually land.

With Firefly

Gallagher keeps Toughness routes alive with heals (and Break-friendly sustain when built that way).

With Mydei

Gallagher covers HP / memosprite upkeep so the Remembrance loop does not collapse mid-wave.

Best Builds (Signature)

Firefly

Light Cone

Whereabouts Should Dreams Rest

Relics

Scholar Lost in Erudition (4pc) + Inert Salsotto (2pc)

Body

CRIT Rate%

Feet

ATK%

Sphere

Fire DMG%

Rope

ATK%

Substats

CRIT Rate ≥ CRIT DMG > ATK% > SPD

Mydei

Light Cone

A Thankless Coronation

Relics

Scholar Lost in Erudition (4pc) + Inert Salsotto (2pc)

Body

CRIT Rate%

Feet

ATK%

Sphere

Imaginary DMG%

Rope

ATK%

Substats

CRIT Rate ≥ CRIT DMG > ATK% > SPD

Who Should You Pull?

Firefly
Pull Firefly if…
  • You need a Fire Destruction unit and Firefly's kit matches your account gap.
  • You prefer Break DPS gameplay over Mydei's Main DPS identity.
  • Yes for Super Break—Firefly remains a top Fire Break carry.
  • Ultimate “Fyrefly Type-IV: Complete Combustion” enters Complete Combustion with full action advance, SPD, and Break-boosted Enhanced attacks.
  • Firefly is a stronger general pull priority for your roster.
Firefly Full Guide
Mydei
Pull Mydei if…
  • You need a Imaginary Destruction unit and Mydei's kit matches your account gap.
  • You prefer Main DPS gameplay over Firefly's Break DPS identity.
  • Yes—Mydei is a strong Imaginary HP-drain Destruction carry.
  • Ultimate “Throne of Bones” Blast-hits the main target plus adjacent enemies.
  • Mydei is a stronger general pull priority for your roster.
Mydei Full Guide