Mortenax Blade Guide and Best Builds

Introductions

Mortenax Blade is a 5-Star Fire character who follows the Path of Nihility. Mortenax Blade is an HP-scaling sub-DPS and support who enters an "Infinite Fury" state through his Ultimate, consuming his HP to deal AoE damage, powerful debuffs, and Follow-Up ATKs.
Our Mortenax Blade Build Guide will show you the best Light Cones, Relics, and Team Compositions to build the most powerful Mortenax Blade you can.

Mortenax Blade's Best Light Cone

The percentage numbers listed showcase the relative DPS increase when you take into account both the Light Cone Effect(s) and Cones Base Stats.

Reforged in Hellfire
S1

Increases the wearer's Max HP by 30.0 / 37.5 / 45.0 / 52.5 / 60.0%. At the start of the wearer's turn, they regenerate a fixed amount of 20.0 Energy. This effect can trigger 1 time each wave. After the wearer uses a Skill Attack, inflicts the target with the "Purgatory" state, lasting for 2.0 turn(s). While in the "Purgatory" state, CRIT DMG taken by the target increases by 30.0 / 37.5 / 45.0 / 52.5 / 60.0%, and CRIT DMG taken from the wearer additionally increases by 30.0 / 37.5 / 45.0 / 52.5 / 60.0%.

Blade's signature Light Cone is generally his strongest option for CRIT teams, granting himself a Max HP increase, Energy on new waves, and applying a debuff that causes enemies to take increased CRIT DMG from the team, and even more from himself.

Lies Dance on the Breeze
S1

Increases the wearer's SPD by 18.0 / 21.0 / 24.0 / 27.0 / 30.0%. After the wearer uses an attack, there is a 120.0% base chance to inflict the "Bamboozle" state on every enemy target. While under the "Bamboozle" state, enemy targets have their DEF decreased by 16.0 / 18.0 / 20.0 / 22.0 / 24.0% for 2 turn(s). If the wearer's SPD is higher than or equal to 170, there is a 120.0% base chance to inflict the "Theft" state on every enemy target. While under the "Theft" state, enemy targets have their DEF decreased by 8.0 / 9.0 / 10.0 / 11.0 / 12.0% for 2 turn(s). When "Bamboozle" or "Theft" is repeatedly inflicted, only the most recently inflicted instance takes effect.

Sources: Event Warp (limited)

This Light Cone provides additional DEF reduction, stacking exceptionally well with the DEF shred from his Ultimate. While this Light Cone impairs Blade's personal damage, it significantly strengthens team damage. Additionally, this Light Cone provides Blade with a high amount of SPD, easing build requirements. Players must prioritize building Mortenax Blade with 28% Effect Hit Rate in order to guarantee this Light Cone applies its debuffs.

Resolution Shines As Pearls of Sweat
S5

When the wearer hits an enemy and if the hit enemy is not already "Ensnared," then there is a 60.0 / 70.0 / 80.0 / 90.0 / 100% base chance to "Ensnare" the hit enemy. "Ensnared" enemies' DEF decreases by 12.0 / 13.0 / 14.0 / 15.0 / 16.0% for 1 turn(s).

Sources: Stellar Warp

This Light Cone provides additional DEF reduction, stacking exceptionally well with the DEF shred from his Ultimate. While this Light Cone impairs Blade's personal damage, it significantly strengthens team damage. Players must prioritize building Mortenax Blade with 67% Effect Hit Rate in order to guarantee this Light Cone applies its debuffs.

Holiday Thermae Escapade
S5

Increases the wearer's DMG dealt by 16.0 / 20.0 / 24.0 / 28.0 / 32.0%. After the wearer attacks, there is a 100% base chance to inflict the attacked target with Vulnerability, increasing the DMG they receive by 10.0 / 11.5 / 13.0 / 14.5 / 16.0% for 2 turn(s). Effects of the same type cannot stack.

Sources: Nameless Glory

This Light Cone provides additional Vulnerability, stacking exceptionally well with the Vulnerability from his Ultimate. While this Light Cone impairs Blade's personal damage, it significantly strengthens team damage. Players must prioritize building Mortenax Blade with 67% Effect Hit Rate in order to guarantee this Light Cone applies its debuffs.

Along the Passing Shore
S1

Increases the wearer's CRIT DMG by 36.0 / 42.0 / 48.0 / 54.0 / 60.0%. When the wearer hits an enemy target, inflicts Mirage Fizzle on the enemy, lasting for 1 turn. Each time the wearer attacks, this effect can only trigger 1 time on each target. The wearer deals 24.0 / 28.0 / 32.0 / 36.0 / 40.0% increased DMG to targets afflicted with Mirage Fizzle, and the DMG dealt by Ultimate additionally increases by 24.0 / 28.0 / 32.0 / 36.0 / 40.0%.

Sources: Event Warp (limited)

While Blade can consistently fulfill this Light Cone's debuff requirement, he is often not the primary damage dealer in the team, incentivizing him to run Light Cones with more supportive capabilities. However, if Mortenax Blade is played as a DPS, this Light Cone becomes significantly stronger.

Before the Tutorial Mission Starts
S5

Increases the wearer's Effect Hit Rate by 20.0 / 25.0 / 30.0 / 35.0 / 40.0%. When the wearer attacks DEF-reduced enemies, regenerates 4 / 5 / 6 / 7 / 8 Energy.

Sources: Mission Reward

A valuable utility option that substantially improves Mortenax Blade's Energy rotations. This Cone is useful for ensuring he re-enters his "Infinite Fury" state as opposed to providing debuffs to enemies.

Good Night and Sleep Well
S5

For every debuff the target enemy has, the DMG dealt by the wearer increases by 12.0 / 15.0 / 18.0 / 21.0 / 24.0%, stacking up to 3 time(s). This effect also applies to DoT.

Sources: Stellar Warp

Similar to more offensive Light Cones, the strength is hindered as he is often not the primary damage dealer in the team, incentivizing him to run Light Cones with more supportive capabilities. However, if Mortenax Blade is played as a DPS, this Light Cone becomes stronger.

Best Relics and Planar Ornaments for Mortenax Blade

Best Relics for Mortenax Blade

These are the best Relic Sets to build for Mortenax Blade.

Divine-Querying Master Smith

2-Piece Set: Increases Max HP by 12.0%.

4-Piece Set: Increases the wearer's CRIT DMG dealt to enemy targets in the DEF reduction state by 28.0%. After the wearer inflicts the DEF reduction state on an enemy target, all allies gain "Comburent" for 2 turn(s). This effect cannot be stacked. DMG dealt by ally targets with "Comburent" increases by 15.0%. This effect can be triggered again after the wearer uses an attack.

Mortenax Blade's strongest Relic Set overall. Since his Ultimate constantly inflicts DEF Shred, he can fully utilize both the CRIT DMG bonus and the teamwide DMG buff with extremely high uptime. This set is ideal for maximizing his personal damage and his supportive capabilities.

Pioneer Diver of Dead Waters

2-Piece Set: Increases DMG dealt to enemies with debuffs by 12.0%.

4-Piece Set: Increases CRIT Rate by 4.0%. The wearer deals 8.0%/12.0% increased CRIT DMG to enemies with at least 2/3 debuffs. After the wearer inflicts a debuff on enemy targets, the aforementioned effects increase by 100%, lasting for 1 turn(s).

A strong alternative due to Blade's ability to maintain debuffs on enemies, as well as contribute significant DMG to allies.

Longevous Disciple

2-Piece Set: Increases Max HP by 12.0%.

4-Piece Set: When the wearer is hit or has their HP consumed by an ally or themselves, their CRIT Rate increases by 8.0% for 2 turn(s) and up to 2 stacks.

A consistent option for the original Blade; since Mortenax Blade constantly consumes his own HP, he can maintain permanent uptime on the CRIT Rate buffs.

Best Planar Ornaments

Bone Collection's Serene Demesne

2-Piece Set: Increases the wearer's Max HP by 12.0%. When the wearer's Max HP is 5000 or higher, increases the wearer's and their memosprite's CRIT DMG by 28.0%.

Mortenax Blade's best Planar Ornament overall. The Max HP is beneficial for a majority of his kit, and the CRIT DMG is strong for his personal DMG.

Inert Salsotto

2-Piece Set: Increases the wearer's CRIT Rate by 8.0%. When the wearer's current CRIT Rate reaches 50.0% or higher, the DMG dealt by the wearer's Ultimate and Follow-Up ATK increases by 15.0%.

A consistent offensive option, increasing both his Ultimate and Follow-Up ATK DMG. Blade's Talent-triggered attacks are also considered a Follow-Up ATK, allowing him to efficiently benefit off of it.

Duran, Dynasty of Running Wolves

2-Piece Set: When an ally character uses a Follow-Up ATK, the wearer gains 1 stack of "Merit," stacking up to 5 time(s). Each stack of "Merit" increases the DMG dealt by the wearer's Follow-Up ATKs by 5.0%. When there are 5 stacks, additionally increases the wearer's CRIT DMG by 25.0%.

A strong option in FUA teams; Blade and his team can efficiently accumulate Merit stacks, allowing him to gain substantial buffs throughout the battle.

Mortenax Blade's Stat Priority

Body

CRIT Rate

CRIT DMG

Feet

SPD

Planar Sphere

Link Rope

Energy Regeneration Rate

Stat Priority

CRIT Rate

CRIT DMG

SPD

Recommended Endgame Stats for Mortenax Blade

6500+

DEF

900+

SPD

134+

Effect Hit Rate

28%/67*

CRIT Rate

90%-100%

CRIT DMG

160%-220%+

Effect Hit Rate is dependent on the Light Cone he has equipped. Verify the stat goal in the Light Cones Section.

Traces Priority

Skills Priority

Ultimate > Skill > Talent > Basic ATK

Major Traces Priority

Heart, Refined ad Infinitum > Bone, Hardened ad Nauseam > Soul, Tempered ad Mortem

Mortenax Blade Build Comments

Mortenax Blade's performance heavily revolves around maintaining uptime on his Ultimate state, "Infinite Fury." While outside this state his damage is extremely limited, once active he becomes a strong debuffer and DMG dealer.

Due to his HP-scaling DMG, Mortenax Blade strongly prefers HP% main stats and substats, especially as it increases his survivability and substantially boosts the damage of nearly every component of his kit.

Energy management is one of the most important aspects of optimizing Mortenax Blade. His A2 Trace, Bone, Hardened ad Nauseam, significantly smooths his rotations by storing excess Energy overflow and immediately restoring Energy after his Ultimate equal to a ratio of the required amount after "Infinite Fury" ends. Energy Regeneration Rate% Link Ropes often outperform HP% ropes in longer encounters due to stronger uptime of "Infinite Fury."

While Mortenax Blade can function as a hypercarry, his strongest teams often involve frequent attackers, such as Ashveil and Tribbie, in which he is a supportive unit with strong damage output. However, Nihility characters are still incredibly viable: the effects provided by Heart, Refined ad Infinitum incentivize using Nihility allies to increase Ultimate DMG for the entire team.

Mortenax Blade's Best Teams

To learn all about Mortenax Blade's synergies and best team compositions, check our dedicated Mortenax Blade team page below:

Mortenax Blade Teams

Mortenax Blade's Best Eidolons

Mortenax Blade's most impactful Eidolons are E1 and E2. His first two Eidolons dramatically improve the consistency and frequency of his Follow-Up ATKs; if you are aiming to invest vertically into Blade, stopping at E1 or E2 is efficient.
Listed below are our thoughts on Mortenax Blade's Eidolons.

Eidolon	Comment
Ere My Death, I Stood Unmade	An efficient Eidolon that increases team DMG with All-Type RES PEN while extending "Infinite Fury" uptime by delaying his Countdown after a Talent-procced Skill. This ability can stack infinitely.
Ash Was My Heart, Yet the Flame Stayed	One of Mortenax Blade's strongest Eidolons; increasing the DMG of his Talent-procced Skill while allowing Ultimates from other allies to count as Follow-Up ATKs, enabling an abundance of effects.
Across the Shore, Wrath Laid Bare	A poor Eidolon that increases the levels of his Ultimate and Talent.
Odium I've Smitten, Thence Came the Blade	A decent Eidolon that increases team DMG.
I Severed My Woes, Knowing Death Begets Life	A poor Eidolon that increases the levels of his Skill and Basic ATK.
If Immortality Could Die, I Swore THEM Slain	An exceptional Eidolon that allows Mortenax Blade to generate Charge whenever he takes damage or consumes HP, increasing his Talent-procs. Additionally, his Skill receives a significant multiplier value increase, strengthening his personal DMG output.

Camaraderia

Staff Author

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This guide is written by camaraderia, a Honkai: Star Rail theorycrafter focused on spreadsheets, optimization, and build recommendations for all characters. He regularly maintains a comprehensive list of resources for upcoming characters and an active theorycrafting community, helping players with realistic assumptions across all investment levels.