The Short Answer
Mortenax Blade is a 5-star Fire/Nihility debuffer who launched in Version 4.3. He functions as a general-purpose damage amplifier and tank hybrid, generating stacks for Acheron through a built-in Taunt mechanic and buffing his entire team through vulnerability and CRIT DMG debuffs. His best relic set is the Divine-Querying Master Smith, his signature light cone is Reforged in Hellfire, and his most impactful slot is in an Acheron-led team. If you already run Acheron as your main DPS, Mortenax Blade is the strongest single pull you can make right now.
New to HSR gearing? Read the relics and light cones guide first, then come back here.
Role Overview
Mortenax Blade occupies a rare dual role: debuffer and front-line tank. His A3 trace, Soul Tempered ad Mortem, forces enemies to attack him periodically, and every attack he receives generates stacks for himself and for any Acheron on the team through his ally loop. His A4 trace, Heart Refined ad Infinitum, unlocks the full team Ultimate DMG buff when Acheron's Nihility requirement is satisfied.
He can also be slotted into generic hypercarry teams as a flexible debuffer and sustain-light tank. He is not a pure damage dealer, so CRIT investment is balanced against HP and Speed thresholds.
Best Relics
4-Piece Set: Divine-Querying Master Smith
This is Mortenax Blade's clear best-in-slot relic set. The 2-piece bonus grants HP%, which directly amplifies his personal damage since he scales off HP. The 4-piece activates the Comburent effect, giving CRIT DMG and providing a 15% damage bonus to all allies, which is one of the most potent team-wide buffs available at the relic layer.
| Slot | Main Stat | Notes |
| Head | HP (flat) | Fixed |
| Hands | ATK (flat) | Fixed |
| Body | CRIT Rate or CRIT DMG | Balance toward 1:2 ratio |
| Feet | Speed | 134+ SPD breakpoint is the first target |
| Sphere | Fire DMG% | His personal damage is Fire-typed |
| Rope | Energy Regeneration Rate | Gets his Ultimate online faster, enabling more debuff cycles |
Planar Ornaments (2-Piece): Sprightly Vonwacq
Vonwacq is the correct Planar choice. It increases Energy Regeneration Rate, pushing Mortenax Blade to his Ultimate on the first turn after spawning, which is critical because his debuffs need to be active before your DPS acts. The Speed passive from its set bonus also contributes to hitting the 134 SPD breakpoint more easily.
Best Light Cones
| Priority | Light Cone | Why |
| 1st (BiS) | Reforged in Hellfire | His signature. Passively grants 30% max HP and restores 20 Energy at the start of each turn, solving both his HP scaling and Energy needs simultaneously. Also boosts CRIT DMG significantly. |
| 2nd | Before the Tutorial Mission Starts | Strong F2P option from the Embers Exchange. Raises CRIT Rate when the target has reduced DEF, synergizing with his debuff kit. |
| 3rd | Resolution Shines as Pearls of Sweat | Farmable from the Forgotten Hall. Applies Vulnerability to enemies, adding more team damage layered on top of his other buffs. |
| 4th | Holiday Thermae Escapade | Accessible alternative with solid HP and team utility. Use until a better option is available. |
Avoid attack-scaling light cones. Mortenax Blade's personal damage scales off HP, so stacking ATK through his light cone is inefficient.
Stat Priorities and Targets
- CRIT Rate: 80% or higher. His Taunt-generated hits need to crit consistently for reliable stack generation.
- HP: 5,000 or higher. Feeds both his personal damage output and his survivability against the attacks his Taunt attracts.
- Speed: 134+. Hitting this breakpoint means he acts before most enemies on the first cycle, getting his debuffs up before the DPS's first big hit.
- CRIT DMG: Stack after hitting CRIT Rate and HP floors. The relic set already provides some, so substats can build on it.
- Energy Regeneration Rate: Covered mostly by Vonwacq Rope. Supplements from substats if his Ultimate feels delayed.
Team Compositions
Acheron Synergy Team (Recommended)
| Character | Role |
| Acheron | Main DPS, consumes stacks from Mortenax Blade's Taunt loop |
| Mortenax Blade | Debuffer, Taunt tank, Nihility requirement filler |
| Second Nihility | Jiaoqiu or Pela (both qualify and add independent debuffs) |
| Sustain | Lingsha, Luocha, or Gallagher |
This team works because Acheron needs two Nihility allies to unlock her full damage bonus, and Mortenax Blade counts as one. His Taunt loop generates Acheron stacks autonomously, and his A4 trace unlocks the Ultimate DMG buff across the whole team. The result is significantly more stack generation than a standard Acheron team, translating directly to more Ultimate casts.
Generic Hypercarry Team
| Character | Role |
| Any hypercarry DPS | Main damage source |
| Mortenax Blade | Vulnerability debuffer, Taunt tank |
| Hypercarry support | Robin, Bronya, Sparkle, or Ruan Mei |
| Sustain | Healer or shielder of choice |
This works well for players who want Mortenax Blade's debuffs without committing to an Acheron-specific account. He loses the synergy bonuses but still contributes meaningful vulnerability and a solid personal damage share.
Should You Pull Mortenax Blade
He is a high-value pull for Acheron accounts and a meaningful upgrade for any team needing a debuffer who can also absorb hits. If you do not own Acheron, he is still useful in general teams but less uniquely powerful. Check the HSR tier list for how he ranks against the current patch units, and claim free Stellar Jade from the codes page to top up your reserves before 4.3 ends.
Keep Building
Once Mortenax Blade is geared, build your full team around him. The HSR best characters guide covers who pairs best with Nihility units right now. The relics guide has the full framework if you need to build multiple carries simultaneously.
