Mortenax Blade is back in Honkai: Star Rail Version 4.6 Phase 2, running from October 21 to November 10. He is a 5-star Fire Nihility character who shreds enemy defenses, amplifies team damage, and keeps himself alive through a self-sustaining HP loop that makes him one of the most flexible debuffers in the current meta. Here is everything you need to build him correctly.
Fornax Ex Corpore zone active
What does Mortenax Blade actually do?
His kit revolves around a single central mechanic: his Ultimate, Fornax Ex Corpore, applies Balefire Bind to all enemies, reducing their DEF by 30% and increasing all damage they take by 50% for 2 turns. It then deploys a Zone that puts him into the Infinite Fury state, unlocking his Skill and enhancing his Basic ATK.
While the Zone is active, every ally attack on an enemy re-applies Balefire Bind and grants Mortenax Blade 1 Charge. At 9 Charge, he fires an extra Skill as a Follow-Up ATK and regenerates 25 Energy. His Bonus Ability Bone, Hardened ad Nauseam lets him bank up to 80 overflow Energy, then convert it back after his next Ultimate. The result is a character who can cycle his Zone almost indefinitely as long as the team attacks frequently.
The self-HP cost matters too. His Skill consumes 10% Max HP, his Ultimate consumes 20%, and if he takes a killing blow he automatically exits the Zone, recovers 50% Max HP, and his Energy resets to at least 75%. This makes him effectively unkillable in most content as long as you keep his Ultimate cycling.
Is Mortenax Blade worth pulling in Version 4.6?
Yes, for most accounts. He slots into Acheron teams as a second Nihility unit, satisfying her Trace requirement while applying independent DEF reduction. He also works in Follow-Up ATK teams alongside Ashveil or Feixiao, where his Charge loop feeds off their rapid multi-hit attacks. If you already own either of those carries, Mortenax Blade meaningfully increases their output.
His signature Light Cone, Reforged in Hellfire, is worth pulling if you plan to use him as a hybrid DPS. If you are saving for future banners, the 4-star Before the Tutorial Mission Starts is the strongest free alternative because it provides Effect Hit Rate and regenerates 4 Energy whenever he attacks a DEF-reduced enemy, which is essentially always.
What are the best light cones for Mortenax Blade?
| Light Cone | Rarity | Why It Works |
|---|---|---|
| Reforged in Hellfire | 5-star (Signature) | +30% Max HP, regenerates 20 Energy at turn start once per wave, applies Purgatory debuff for +30% CRIT DMG taken by enemies |
| Lies Dance on the Breeze | 5-star | Boosts SPD and applies Bamboozle/Theft DEF reduction on top of his own |
| Before the Tutorial Mission Starts | 4-star | +20% Effect Hit Rate, regenerates 4 Energy on attacks against DEF-reduced enemies |
| Resolution Shines As Pearls of Sweat | 4-star | Applies Ensnare DEF reduction for extra shred stacking |
| Holiday Thermae Escapade | 4-star | Increases his own DMG and enemy DMG taken |
What relics should Mortenax Blade use?
Best-in-slot: 4-piece Divine-Querying Master Smith
The 2-piece bonus increases Max HP by 12%, directly boosting all his HP-scaling damage. The 4-piece bonus increases his CRIT DMG against DEF-reduced enemies by 28% and grants all allies the Comburent buff for 2 turns after he applies DEF reduction, increasing their DMG dealt by 15%. Since Balefire Bind re-applies on every ally attack, Comburent is essentially permanent.
Second option: 4-piece Eagle of Twilight Line
Advances Mortenax Blade forward after each Ultimate use, giving him more turns and faster Energy cycling. Useful if you want him acting more frequently rather than maximizing personal damage.
Planar Ornaments:
- Sprightly Vonwacq (Best): +5% Energy Regeneration Rate, advances him forward 40% at battle start when SPD reaches 120+. This lets him set up his Zone before enemies act.
- Bone Collection's Serene Demesne: +Max HP and CRIT DMG if you already have reliable Energy uptime.
- Lushaka, the Sunken Seas: Energy Regen plus ATK boost for the first-slot ally.
Best-in-slot relic set
What main stats and substats does Mortenax Blade need?
| Piece | Main Stat |
|---|---|
| Body | CRIT Rate (priority) or Effect Hit Rate |
| Feet | Speed |
| Planar Sphere | HP% or Fire DMG% |
| Link Rope | Energy Regeneration Rate (priority) or HP% |
Substat priority: CRIT Rate = CRIT DMG > Speed > HP%
Recommended stat thresholds:
- HP: 6,000 or above
- CRIT Rate: as close to 100% in combat (his Ultimate provides +20% CRIT Rate while active)
- CRIT DMG: 120% or above before combat
- Speed: any breakpoint between 134 and 160
The mistake most players make here is ignoring HP% entirely in favor of pure crit. His Skill deals Fire DMG equal to 72% Max HP to all enemies plus 4 additional instances at 24% Max HP each. Every HP point is a damage multiplier.
Trace priority
Level his abilities in this order:
- Ultimate (highest priority) - increases DEF reduction, DMG received debuff, and his own CRIT DMG buff
- Talent - increases Energy regenerated per Charge cycle, keeping his Zone active longer
- Skill - increases AoE and random-target damage
- Basic ATK (lowest priority) - only increases basic damage, skip until everything else is maxed
Bonus Abilities to unlock first:
- Bone, Hardened ad Nauseam (A2) - the overflow Energy mechanic that makes him functionally immortal
- Heart, Refined ad Infinitum (A6) - the team damage amplification
- Soul, Tempered ad Mortem (A4) - increased taunt, 50% DMG reduction, and +50% Incoming Healing while Zone is active
What are the best teams for Mortenax Blade?
Ashveil Follow-Up core (highest ceiling)
Ashveil's rapid multi-hit Follow-Up attacks fill Mortenax Blade's Charge almost immediately after his Zone deploys. Tribbie adds Vulnerability and All-Type RES PEN, and Hyacine or Dan Heng Permansor Terrae provides HP-scaling sustain that also inflates Mortenax Blade's damage numbers.
Rotation: Use Mortenax Blade's Technique to Taunt before combat, then Ultimate as soon as possible. Once Balefire Bind is up, Ashveil chains Follow-Ups while Mortenax Blade fires extra Skills through Charge. The Zone stays active almost permanently.
Acheron Nihility team
Mortenax Blade satisfies Acheron's requirement for Nihility allies, applies independent DEF reduction and Vulnerability, and generates Nihility stacks through Balefire Bind re-applications. The Ultimate DMG buff from Heart, Refined ad Infinitum stacks directly with Acheron's own multipliers.
Recommended compositions:
- Acheron + Mortenax Blade + Jiaoqiu + Hyacine
- Acheron + Mortenax Blade + Cipher + Huohuo
- Acheron + Mortenax Blade + Pela + Gallagher (budget)
F2P and beginner options
If you're struggling with limited 5-star supports, Dr. Ratio + Mortenax Blade + Welt + Gallagher is the most consistent budget team. Mortenax Blade's Balefire Bind applies DEF reduction and Vulnerability, Welt adds Slow and Imprisonment, and Gallagher's Besotted debuff completes the three-debuff floor that guarantees Dr. Ratio's Follow-Up ATK trigger.
| Team Archetype | Core Units | Best Content |
|---|---|---|
| Ashveil FuA | Ashveil, Mortenax Blade, Tribbie, Hyacine | MoC, Pure Fiction, endgame |
| Acheron Nihility | Acheron, Mortenax Blade, Jiaoqiu, sustain | MoC single-target, Apocalyptic Shadow |
| Mortenax Blade Hypercarry | Mortenax Blade, Sunday/Sparkle, Tribbie, healer | Zone-uptime content |
| Budget FuA | Dr. Ratio, Mortenax Blade, Welt, Gallagher | Early/mid accounts |
For more team-building ideas across the roster, the full Honkai: Star Rail strategy guides cover a wide range of characters and compositions.
Ashveil FuA core lineup
Eidolons: where to stop spending
E1 - Ere My Death, I Stood Unmade: Reduces all enemies' All-Type RES by 20% while the Zone is active and delays the Infinite Fury countdown by 15% after using the Talent's extra Skill. Strong support Eidolon that directly boosts team damage.
E2 - Ash Was My Heart, Yet the Flame Stayed: The best stopping point for spenders. Makes all ally Ultimates count as Follow-Up ATKs, increases Follow-Up ATK DMG for all allies by 75%, and reduces Mortenax Blade's Charge threshold from 9 to 7. This opens up massive synergy with Ashveil and any FuA-focused team.
E4 - Odium I've Smitten, Thence Came the Blade: Adds another 50% DMG boost to all allies through Heart, Refined ad Infinitum. Good value but not a priority over E2.
E6 - If Immortality Could Die, I Swore THEM Slain: Grants 1 Charge whenever Mortenax Blade takes damage or consumes HP (once per turn end), and multiplies Tenax Per Ignem's damage to 150% of its original value. Massive personal DPS increase, but E2 provides more team-wide value per Eidolon spent.
Trust me on this one: E0 is already strong, E1 is a solid pickup, and E2 is the wall. Everything past that is diminishing returns unless you specifically want him as a hypercarry DPS.
Ascension and trace materials
To fully ascend Mortenax Blade to level 80 you need: 15x Lucid Awl, 15x Dreamweave Steel, 15x Whimsy Wax, 65x Radiant Prominence, and 308,000 Credits. Maxing all four traces requires an additional 3,000,000 Credits, 139x Heart of Phagousa, 72x Wine of Phagousa, 15x Tear of Phagousa, 8x Tracks of Destiny, and the same Whimsy Wax, Dreamweave Steel, and Lucid Awl used for ascension.
Farm Phagousa materials from the current patch content and prioritize Tracks of Destiny from the Simulated Universe or monthly shop.
How does Mortenax Blade fit into the Version 4.6 meta?
Version 4.6 also introduces Pearl, a Preservation/Elation hybrid who rewards full Elation team compositions. Mortenax Blade operates in a completely different ecosystem (Nihility and FuA), so the two characters are not competing for the same roster slots. If you are building Elation teams around Pearl, check out the Pearl build guide covering relics, teams, and pull value for a full breakdown.
For players invested in other archetypes this patch, the Evanescia build guide covers her Elation DPS kit in detail, and the Robin Summeretto build guide is worth reading if you are running Follow-Up teams and want to understand how action advance interacts with Mortenax Blade's Charge loop.
Common mistakes to avoid
- Not building enough HP: His damage scales entirely off Max HP. A CRIT-heavy build with low HP underperforms compared to a balanced HP/CRIT setup.
- Skipping Energy Regen on the rope: Without consistent Ultimate cycling, his Zone drops and the entire kit falls apart. Energy Regen Rate rope is almost always better than HP% rope unless you are already hitting your Ultimate every two turns.
- Running him without a healer in early clears: His immortality loop requires specific timing. Until you understand the Zone mechanics, bring a healer to cover gaps.
- Ignoring Sprightly Vonwacq: The action advance at battle start lets him deploy his Zone before enemies act, which is the difference between a smooth rotation and scrambling to set up debuffs.
Frequently asked questions
Does Mortenax Blade need his signature Light Cone? No. Before the Tutorial Mission Starts at S5 is a strong free alternative. His signature improves his HP, Energy cycling, and team CRIT DMG taken, but the kit functions without it.
Can Mortenax Blade run sustainless? Yes, especially with Acheron teams where Welt provides enemy delay. His Taunt and HP recovery mechanic absorb incoming hits, and the Zone's 50% DMG reduction keeps him alive through most content.
What Speed should Mortenax Blade run? Any breakpoint between 134 and 160. Higher Speed means more turns and faster Charge accumulation, but do not sacrifice CRIT stats to chase Speed beyond 160.
Does E2 work with Acheron's Ultimate? Yes. E2 makes all ally Ultimates count as Follow-Up ATKs, which means Acheron's Ultimate receives the 75% Follow-Up ATK DMG boost. This is one of the strongest Eidolon interactions in the current patch.
