Mortenax Blade is the highly anticipated 5-star Fire Nihility character arriving in Honkai: Star Rail version 4.3. As a special form of the Stellaron Hunter Blade, he brings a dramatic rework that blends high-risk HP consumption mechanics with powerful team-wide debuffs, zone-based support, and strong personal damage through follow-up attacks.

This preview build guide is based on current beta information and may see adjustments upon official release. Mortenax Blade excels as a flexible sub-DPS and support who shines in follow-up attack teams or Nihility-heavy compositions while scaling primarily off Max HP.

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Quick Overview

  • Rarity: 5-star
  • Element: Fire
  • Path: Nihility
  • Role: Hybrid support/sub-DPS with zone deployment, DEF shred, vulnerability debuffs, and HP-scaling AoE damage
  • Key Mechanic: Deploys a Zone via Ultimate to enter "Infinite Fury" state, unlocking enhanced abilities, CRIT buffs, and Charge generation for extra Skills treated as follow-up attacks

Kit Highlights

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Mortenax Blade's playstyle revolves around his Ultimate, which applies Balefire Bind (DEF reduction and increased damage taken) to enemies while consuming HP to create a Zone. While the Zone is active, he gains significant CRIT Rate and CRIT DMG, his Skill becomes freely usable without Skill Points in many cases, and he generates Charges from ally attacks to unleash powerful follow-up Skills.

His Basic Attack also applies Taunt, helping him draw aggression while tanking in the Zone thanks to damage reduction traces.

Best Light Cones

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Signature Light Cone (Best in Slot): Reforged in Hellfire (or equivalent signature)
This cone boosts Max HP, provides Energy regeneration, and adds strong CRIT DMG taken debuffs on targets hit by his Skill. Perfect synergy with his kit.

Strong Alternatives:

  • Lies Dance on the Breeze (excellent SPD and DEF reduction)
  • Before the Tutorial Mission Starts (Effect Hit Rate and Energy on debuffed enemies)
  • In the Name of the World or other Nihility options focused on debuff amplification and damage to weakened foes

Prioritize Light Cones that increase HP, Energy regen, or amplify damage against debuffed enemies.

Best Relics and Planar Ornaments

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Relic Set Recommendations:

  • Divine-Querying Master Smith (4-piece): Top choice. Provides Max HP and CRIT DMG to DEF-reduced enemies while granting allies a damage buff ("Comburent") when you apply DEF reduction.
  • Pioneer Diver of Dead Waters (4-piece): Strong for debuff-focused play, boosting damage to debuffed enemies and CRIT stats.
  • Longevous Disciple (4-piece): Good for survivability with HP and CRIT Rate stacks from being hit or consuming HP.

Planar Ornaments:

  • Sets that offer HP% or CRIT Rate/DMG bonuses.
  • Options like Bone Collection's Serene Demesne for additional CRIT DMG at high HP thresholds or Inert Salsotto for Ultimate and follow-up attack boosts.

Stat Priority:

  • Body: CRIT DMG (or CRIT Rate if needed for balance)
  • Feet: SPD (aim for comfortable speed to act frequently in the Zone)
  • Planar Sphere: Fire DMG Boost or HP%
  • Link Rope: HP%
  • Substats: HP% > CRIT Rate = CRIT DMG > SPD > Effect Hit Rate (for debuffs)

Focus on reaching solid HP pools (5000+ for many set bonuses) while balancing CRIT stats. His Infinite Fury state already provides strong CRIT buffs.

Best Team Compositions

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Mortenax Blade is versatile and works well in several archetypes:

  1. Follow-up Attack Focused: Mortenax Blade + Ashveil + Tribbie + Dan Heng • Imbibitor Lunae (or similar FuA enablers). His Charges generate quickly from ally follow-ups.
  2. Nihility Hypercarry: Mortenax Blade + Acheron + Sparkle + sustain. Extra benefits if other Nihility characters are present for his traces.
  3. General Support/DPS Hybrid: Flexible with many teams that benefit from DEF shred and team DMG% buffs in his Zone.

He pairs especially well with characters who frequently use Ultimates or follow-up attacks.

Ascension and Trace Materials

Ascension Materials (approximate totals):

  • 308K Credits
  • 15 Whimsy Wax
  • 15 Dreamweave Steel
  • 65 Radiant Prominence
  • 15 Lucid Awl

Trace Materials (approximate totals):

  • 3M Credits
  • Various Phagousa items (Tear, Wine, Heart of Phagousa)
  • Whimsy Wax, Dreamweave Steel, Lucid Awl
  • 12 Vanquished Flow's Reticence
  • 8 Tracks of Destiny

Farm the new materials introduced or featured in version 4.3 for efficient pre-farming.

Playstyle Tips

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  • Use Ultimate to deploy the Zone early and enter Infinite Fury for massive power spikes.
  • Manage HP carefully. His kit involves frequent self-damage, but traces provide healing and survival on lethal hits.
  • Position him to benefit from Taunt while allies pile on debuffed enemies.
  • In the Zone, focus on generating Charges through ally actions to trigger free follow-up Skills for extra damage and Energy.
  • At E0 he is already strong as a team enabler; higher Eidolons add RES shred, more Charges, and further damage multipliers.

Eidolons Snapshot

  • E1: All-Type RES shred in Zone + delayed Zone countdown.
  • E2: Massive boosts to follow-up mechanics and ally Ultimate interaction.
  • E4 and E6: Further team DMG% and personal Ultimate multipliers.

Mortenax Blade looks set to be a standout unit in version 4.3, offering fresh gameplay for Blade fans and strong utility for many endgame teams. Pre-farm HP-focused relics and the relevant materials now to hit the ground running when his banner "Now I Am Become Blade" drops in Phase 1.