Necrobinder — Slay the Spire 2 Character Guide
“A Spireborn lich who seeks revenge. Calls upon her trusty left hand, Osty, in combat.”
A Spireborn lich with her loyal bodyguard Osty. Osty blocks attacks for you, creating an extra HP layer. The Necrobinder offers doom, ethereal, and summon archetypes — high ceiling but a steep learning curve.
Resource System: Standard Energy (3 per turn) plus Osty's HP (separate health bar that absorbs damage). Souls serve as a secondary engine for draw and damage.
Unlock: Play a run as the Regent.
Best For: Veterans who love complex, high-risk-high-reward gameplay. Mastering the Necrobinder is the ultimate Slay the Spire 2 challenge.
Necrobinder Core Mechanics — Detailed Breakdown
The Necrobinder is Slay the Spire 2's most complex and rewarding character — a Spireborn lich who commands her loyal companion Osty, inflicts the devastating Doom debuff, and generates Souls for powerful synergies. With three interlocking mechanical systems, the Necrobinder has the steepest learning curve in the game but also one of the highest ceilings. Mastering her means understanding when to invest in Osty, when to focus on Doom, and when to generate Souls for explosive combo turns.
Osty is the Necrobinder's defining feature.
At the start of each combat, the Necrobinder summons Osty via Die For You. Osty has a separate HP bar (starting at 1 HP) and automatically intercepts attacks aimed at the Necrobinder. This creates an extra damage soak layer — enemies have to kill Osty before they can damage you. Summon effects add HP to Osty, and if Osty dies, the next Summon effect revives it at 1 HP. This means Osty is never permanently gone — but keeping it alive with substantial HP is the key to the Necrobinder's survivability. Critically, Osty's attacks and effects are completely independent of the Necrobinder's buffs and debuffs. If the Necrobinder has reduced Strength or is Weakened, Osty cards still deal their full listed damage.
Doom is the Necrobinder's signature execution mechanic.
When you deal damage that applies Doom, the enemy accumulates a purple Doom counter on their health bar. If Doom ever equals or exceeds the enemy's current HP, that enemy is marked for instant death at the end of its next turn. This effectively doubles your damage output — direct damage reduces HP while Doom builds toward the execution threshold. Against enemies with 200 HP, you only need to deal 100 damage through Doom-applying attacks to trigger the execution. The power card that makes all damage apply Doom is the most important card in the Doom archetype, turning every single attack into double damage.
Soul generation is the Necrobinder's engine mechanic.
Souls are generated by specific cards like Grave Warden (the best common card), Reave, Severance, and Capture Spirit. Souls fuel draw effects, damage scaling based on Soul count, and powerful burst plays. Grave Warden is almost always worth picking up and is a high-priority upgrade because consistent Soul generation enables the rest of the Necrobinder's kit. Without Soul generation, the Necrobinder's deck feels sluggish and underpowered — with it, she can chain devastating combos that other characters can't replicate.
The Necrobinder also features Ethereal cards and sacrifice synergies.
Ethereal cards are discarded at the end of your turn if not played, creating a use-it-or-lose-it tension. Some of her most powerful effects have the Ethereal keyword, meaning you must prioritize playing them or lose their value. Sacrifice effects let you intentionally destroy Osty or spend HP for powerful bonuses. This risk-reward dynamic is central to the Necrobinder's identity — she trades safety for power, making her the most demanding character in terms of moment-to-moment decision-making. The lowest base HP in the game at 66 reinforces this glass-cannon identity.
Necrobinder Playstyle & Strategy Tips
Either turn Osty into a five-finger death punch (Dirge, Wisps, Borrowed Time, Invokes for insane summon buildup) or focus on inflicting Doom to bypass defenses. Soul generation is nearly mandatory — Grave Warden is the best common and a high-priority upgrade. Cards like Reave, Severance, and Capture Spirit provide supplemental soul generation. Mixing doom and Osty attacks works well with enough soul generation.
The Necrobinder starts with Necro Strike, Necro Defend, Bodyguard, Unleash, and the automatic Die For You (which summons Osty). Bodyguard adds HP to Osty, keeping your damage soak alive. Unleash deals damage — basic but functional. Your early priority is finding Grave Warden for Soul generation and deciding between Osty-focused or Doom-focused builds.
Necrobinder Traits & Abilities Explained
Osty Summon
Osty is the Necrobinder's loyal companion, summoned at the start of every fight. Osty has a separate HP bar and automatically absorbs attacks aimed at you. Summon effects add HP to Osty — the higher Osty's HP, the more damage it can absorb. If Osty dies, the next Summon effect revives it at 1 HP. Osty cards deal damage independently of the Necrobinder's stats — debuffs on you don't affect Osty's damage. Cards like Dirge, Wisps, and Invokes are core Osty-buffing cards.
Doom Mechanic
Doom is a purple counter applied to enemies. When Doom equals or exceeds an enemy's current HP, that enemy dies at the end of its next turn regardless of Block or other defenses. The key power card that makes ALL damage apply Doom is the build-defining card for Doom archetypes. With this power active, a 10-damage attack reduces HP by 10 AND applies 10 Doom, effectively dealing 20 HP worth of progress toward killing the enemy. Doom bypasses healing and regeneration — once marked for death, the enemy cannot escape.
Soul Generation
Souls are generated by specific Necrobinder cards and serve as an engine resource for draw, damage, and burst effects. Grave Warden generates Souls consistently and is the best common card in the Necrobinder's kit. Souls fuel cards that deal damage based on Soul count, enable extra draws, and power explosive sacrifice effects. Without reliable Soul generation, the Necrobinder's kit doesn't function — prioritize picking up Grave Warden and similar Soul-generating cards early.
Ethereal Cards
Some Necrobinder cards have the Ethereal keyword — if not played by end of turn, they are discarded automatically. This creates use-it-or-lose-it decisions each turn. Ethereal cards tend to be more powerful than their non-Ethereal equivalents to compensate for this restriction. Managing Ethereal cards requires planning your turn order carefully to ensure you play high-value Ethereal cards before ending your turn.
Sacrifice Synergy
Several Necrobinder cards let you sacrifice Osty's HP, your own HP, or cards for powerful effects. These sacrifice effects embody the Necrobinder's risk-reward identity — you trade safety for power. Blowing up Osty for damage, spending HP for Soul generation, or exhausting cards for burst effects are all part of the Necrobinder's toolkit. The key is knowing when the sacrifice is worth it and when preserving resources is more important.
Necrobinder Strengths & Weaknesses
Strengths
Osty Creates an Extra HP Layer
No other character has a damage soak like Osty. With enough Summon investment, Osty can absorb 20-40 damage per turn, effectively doubling or tripling the Necrobinder's survivability. Enemies must kill Osty before they can touch your 66 HP, and Osty automatically revives with the next Summon effect.
Doom Bypasses Massive HP Pools
When Doom equals or exceeds enemy HP, instant death triggers regardless of Block, healing, or other defenses. Against Act 3 bosses with 300+ HP, the Necrobinder only needs to deal 150 damage through Doom-applying attacks to trigger the execution. This cuts kill time in half compared to other characters.
Soul Engine Enables Explosive Turns
Soul generation powers the Necrobinder's draw engine and burst damage. With enough Souls, you can draw your entire deck in a single turn and chain devastating combos. Soul-based damage scaling means a single card can deal 50+ damage when your Soul count is high.
Osty Is Immune to Your Debuffs
Osty's attacks are completely independent of the Necrobinder's buffs and debuffs. If you're Weakened, Strength-reduced, or otherwise debuffed, Osty cards still deal their full listed damage. This makes the Necrobinder uniquely resistant to debuff-heavy enemies that cripple other characters.
Weaknesses
Lowest Base HP in the Game
At 66 HP, the Necrobinder has 14 less than the Ironclad and 4-9 less than every other character. Without Osty absorbing hits, even small mistakes can be fatal. You cannot afford to take unblocked hits in Acts 2-3, making early-game Summon investment critical.
Three Interlocking Systems to Manage
Osty management, Doom application, and Soul generation are three separate systems that all need attention. Neglecting Osty means you take too much damage. Neglecting Doom means fights take too long. Neglecting Souls means your engine stalls. Balancing all three simultaneously is the Necrobinder's core challenge.
Doom Is Slow Against Very High HP Enemies
While Doom effectively halves the damage needed to kill enemies, against bosses with 500+ HP, you still need to deal 250 damage through Doom-applying attacks. If your Doom engine isn't fully online by Act 3, boss fights can drag out dangerously.
Osty Dying at the Wrong Time Is Catastrophic
If a big hit kills Osty and you don't have a Summon card in hand, the next enemy attack hits your 66 HP directly. Against Act 2+ enemies that deal 20-30 damage per hit, losing Osty without a Summon backup can end the run in a single turn. Always keep a Summon card ready.
Necrobinder Starting Deck Strategy
The Necrobinder starts with Necro Strike, Necro Defend, Bodyguard, Unleash, and the automatic Die For You (which summons Osty). Bodyguard adds HP to Osty, keeping your damage soak alive. Unleash deals damage — basic but functional. Your early priority is finding Grave Warden for Soul generation and deciding between Osty-focused or Doom-focused builds.
Necro Strike
Usage
Basic attack dealing 6 damage. Standard starting card with no special synergies. Outclassed quickly by Doom-applying attacks or Osty attack cards.
Upgrade Priority
Very Low. Literally any Necrobinder-specific card is a better upgrade target.
When to Replace
Remove at first opportunity. The Necrobinder has much better damage sources through Doom and Osty.
Necro Defend
Usage
Basic 5-Block skill. Important early because the Necrobinder's 66 HP means every point of Block matters. Osty eventually takes over the defensive role.
Upgrade Priority
Low. Defend+ is fine but Bodyguard and Soul-generating cards are better upgrade targets.
When to Replace
Replace once Osty is reliably absorbing enough damage. Keep 2-3 until your Summon engine is consistent.
Usage
Adds HP to Osty (Summon effect). Your primary way to keep Osty alive in the early game. Play it every turn you draw it — a dead Osty means you take direct damage.
Upgrade Priority
High. Bodyguard+ adds more HP to Osty, making your primary defensive layer more robust. One of the best early upgrades.
When to Replace
Keep long-term. Summon effects are always valuable for maintaining Osty's HP. Only consider replacing in pure Doom builds that don't focus on Osty.
Usage
Basic damage card with light synergy with Osty effects. Deals moderate damage and may interact with Osty's attack state.
Upgrade Priority
Medium. Unleash+ improves combat efficiency. Upgrade after Bodyguard but before basic Strikes.
When to Replace
Replace with Doom-applying attacks or stronger Osty attack cards as they become available.
Starting Deck
Necrobinder Card Tier List — Must Pick, Great, Situational & Skip
Grave Warden
The best common card in the Necrobinder's kit. Generates Souls consistently, enabling the entire Soul engine. Always pick, always upgrade.
Doom Power
Makes ALL damage apply Doom. Effectively doubles your damage output. The single most important card for Doom archetypes.
Dirge
Powerful Osty buffing card that adds significant HP and attack power. Core card for Osty-focused builds.
Reave
Deals damage and generates Souls. Combines offense with engine-building. Essential for Soul-based strategies.
Wisps
Adds substantial Osty HP through multiple Summon triggers. Combined with Osty attack cards, turns Osty into an offensive and defensive powerhouse.
Borrowed Time
Powerful combo enabler that interacts with Soul generation and Osty mechanics. High-ceiling card in the right build.
Severance
Soul generation with damage. Reliable secondary Soul source when Grave Warden isn't enough.
Capture Spirit
Generates Souls from enemy deaths. Excellent in multi-enemy fights where Soul generation accelerates.
Invokes
Powerful Osty buff that increases both HP and attack. Scales Osty into a formidable combat presence.
Dark Pact
Sacrifice-based draw and damage. Trades safety for card advantage, fitting the Necrobinder's risk-reward identity.
Binding
Doom application with utility. Applies Doom while providing defensive or control effects.
Soul Harvest
Deals damage based on Soul count. Devastating when Soul generation is high but dead without Souls.
Bone Barrier
Defensive card using Osty mechanics. Good in Osty builds but weak without Summon support.
Phantasm
Ethereal high-damage card. Strong when played on time but wasted if you can't play it the turn you draw it.
Necrotic Touch
Applies Doom to a single target. Useful for focused Doom application but outclassed by the Doom power card.
Spectral Chain
Control effect that interacts with Osty. Situationally powerful against specific enemy types.
Weak Summon
Adds too little HP to Osty to be worth a deck slot. Bodyguard is strictly better.
Fading Soul
Generates too few Souls to justify inclusion. Grave Warden generates more with better consistency.
Spectral Strike
Basic attack variant with minimal synergy. The Necrobinder has much better attack options.
Hollow Shell
Defensive card that doesn't interact with Osty, Doom, or Souls. Outclassed by any synergistic option.
Best Relics for Necrobinder
Bronze Scales
Start each combat with 3 Thorns.
Deal 3 damage to attackers whenever you take damage. Since Osty absorbs hits (and Osty taking damage counts), this triggers frequently for free damage.
Torii
Reduce damage to 1 when you take 5 or less damage in a single hit. With Osty absorbing larger hits, the small hits that reach you are reduced to 1.
Meat on the Bone
If your HP is at or below 50% at the end of combat, heal 12 HP.
Gain 12 HP if at half health or below at end of combat. At 66 HP, you'll frequently be below 33 HP, making this trigger very often.
Self-Forming Clay
Whenever you lose HP in combat, gain 3 Block next turn.
Gain 3 Block when you lose HP. Since the Necrobinder takes chip damage frequently, this provides consistent supplemental defense.
Pen Nib
Every 10th Attack you play deals double damage.
Every 10 attacks, deal double damage. Double Doom-applying damage means double Doom stacks, accelerating the execution threshold.
Dead Branch
Whenever you Exhaust a card, add a random card to your hand.
Add a random card to your hand whenever you Exhaust a card. The Necrobinder exhausts Ethereal cards frequently, generating free random cards each turn.
Necrobinder Ascension Tips — How to Push Higher Ascension Levels
At Ascension 1+, Grave Warden is your highest priority pickup in Act 1. Soul generation fuels everything the Necrobinder does. Upgrade Grave Warden at the first rest site.
Ascension 5+ makes Osty management critical. Invest more in Summon effects to keep Osty's HP high. An Osty with 10+ HP per turn is the difference between taking 0 damage and taking lethal damage.
At Ascension 10+, the Doom archetype becomes more important. Fights are too dangerous to outlast — you need to kill enemies faster, and Doom's execution mechanic cuts kill time in half.
Ascension 15+ means the Necrobinder's 66 HP is truly punishing. Take every HP-increasing opportunity — Feed events, max HP relics, and +HP ancients. Every point of HP is worth more on the Necrobinder than any other character.
For Ascension 18+, mixing Doom and Osty strategies is mandatory. Pure Doom is too slow without burst, and pure Osty is too fragile without damage. The strongest Necrobinder builds at high Ascension combine both with strong Soul generation.
At the highest Ascensions, consider keeping Ethereal cards you'd normally skip. Ethereal cards tend to have higher power levels, and at Ascension 20, you need every advantage you can get even if it means managing the Ethereal timing carefully.
Recommended Necrobinder Builds
Necrobinder Osty Build
Turn Osty into an unstoppable force. Stack Summon effects to build Osty's HP, then unleash devastating attacks through Reanimate or sacrifice for massive AoE. Osty acts as both your shield and your weapon.
Dirge
InvokeBorrowed Time
ReanimateOsty is the Necrobinder's loyal companion — it starts each fight at 1 HP and auto-blocks attacks targeting you. Every Summon effect adds HP to Osty. With enough Summon cards, Osty can reach 50-100+ HP, becoming an enormous damage sponge. Reanimate deals damage equal to Osty's current HP. Borrowed Time generates Energy when you Summon. The strategy: feed Osty, protect yourself, then unleash Osty's stored power.
ANecrobinder Doom Build
Apply Doom to enemies until it exceeds their HP, causing instant death. Bypasses all defenses, armor, and scaling. When Doom stacks equal or exceed enemy HP, they die at the end of their next turn. The ultimate inevitability.
Capture Spirit
CountdownGrave Warden
Danse MacabreDoom is a unique debuff: when an enemy's Doom stacks equal or exceed their current HP, they die at the end of their next turn. Unlike Poison or direct damage, Doom bypasses Block, Plated Armor, and defensive buffs entirely. Capture Spirit and Countdown are your primary Doom applicators. Danse Macabre turns every Soul generated into passive Doom on ALL enemies. The strategy is simple: apply Doom, survive, and let inevitability do the rest.
SNecrobinder Soul Build
A card-draw powerhouse that generates Souls (free 0-cost draw-2 Exhaust cards) and converts them into devastating damage via Soul Storm, Haunt, and Death March. By flooding the deck with Souls and playing them for massive draw, every turn becomes an explosive chain of card plays that overwhelm enemies with unstoppable accumulated damage.
Haunt
Soul Storm
Death MarchCapture SpiritSouls are colorless 0-Energy cards that draw 2 cards and Exhaust when played. Soul-generating cards like Capture Spirit (add 3 Souls), Grave Warden (add 1 Soul + Block), and Dirge (add X Souls) fill your draw pile with Souls. The payoff cards — Haunt (6 damage to random enemy per Soul played), Soul Storm (+2 damage per Soul in exhaust pile), and Death March (+3 damage per card drawn) — convert this massive card draw into lethal damage. The longer the fight goes, the stronger Soul Storm becomes as the exhaust pile fills with spent Souls.
ANecrobinder Reaper Build
Transform into the Reaper and harvest enemies with devastating attack scaling. Reaper Form empowers your attacks with lifesteal and bonus damage, while The Scythe and Eradicate provide massive AoE. Unlike Soul or Doom builds, this is pure aggression — attack hard, heal through damage, and overwhelm enemies before they can respond.
Reaper Form
The Scythe
Eradicate
LethalityReaper Form is a Power that grants lifesteal and bonus attack damage. The Scythe deals massive AoE damage. Eradicate provides heavy single-target removal. Lethality adds Strength that amplifies all subsequent attacks. The build plays like a combat berserker: activate Reaper Form for lifesteal, stack Lethality for Strength, then unleash The Scythe and Eradicate for devastating damage that also heals you. Osty serves as a tank while you set up, absorbing hits during the first 1-2 turns.
Necrobinder Cards (88)
All Cards →| Card | Type | Cost | Rarity | Effect |
|---|---|---|---|---|
 | Skill | 1 | Basic | |
 | Skill | 1 | Basic | |
 | Attack | 1 | Basic | |
 | Attack | 1 | Basic | |
 | Skill | 1 | Common | |
 | Attack | 1 | Common | |
 | Attack | 1 | Common | |
 | Skill | 1 | Common | |
 | Attack | 1 | Common | |
 | Attack | 1 | Common |
Necrobinder FAQ — Frequently Asked Questions
What is the best Necrobinder build in Slay the Spire 2?
The Doom + Soul Engine build is the most consistent. Get the Doom power card so all damage applies Doom, generate Souls with Grave Warden and Reave, and use Bodyguard to keep Osty alive for defense. This combination gives you halved kill times through Doom while maintaining survivability through Osty.
How does Osty work?
Osty is summoned at the start of every fight with 1 HP. Osty has a separate health bar and intercepts all attacks aimed at you. Summon effects add HP to Osty. If Osty is killed, the next Summon effect revives it at 1 HP. Osty's attack cards deal damage independently of your buffs and debuffs — if you're Weakened, Osty's attacks are unaffected.
Can Doom kill bosses?
Yes. Doom works on every enemy in the game, including bosses. When Doom on a boss equals or exceeds its current HP, the boss dies at the end of its next turn. Against a boss with 300 HP, you need Doom to reach 300 — but since Doom-applying attacks also deal direct damage, you effectively only need to deal 150 damage to trigger the execution.
Is Grave Warden really the best common card?
Yes. Grave Warden generates Souls, which fuel the Necrobinder's entire draw engine, damage scaling, and burst potential. Without Soul generation, the Necrobinder's kit doesn't function. Grave Warden is the most reliable and consistent Soul source, making it worth picking up and upgrading every time it appears.
Should I focus on Osty or Doom?
Ideally, both. Osty provides defense (absorbing hits) while Doom provides offense (halving kill time). In practice, prioritize whichever you find cards for first. If you get early Summon cards, invest in Osty. If you find the Doom power card, lean into Doom. The best high-Ascension Necrobinder builds combine both with Soul generation.
How do I keep Osty alive?
Play Summon cards (Bodyguard, Dirge, Wisps, Invokes) as often as possible to add HP to Osty. The more HP Osty has, the more hits it can absorb. Always keep at least one Summon card in reserve for emergency Osty revival. In the early game, prioritize Bodyguard plays even over dealing damage.
Why is the Necrobinder rated B-tier?
The B-tier rating reflects consistency, not power ceiling. A mastered Necrobinder can win any fight in the game, but her three interlocking systems, lowest HP, and reliance on specific cards make her the least consistent character for average win rates. She requires more game knowledge and decision-making skill than S-tier characters to achieve similar results.
What are the best relics for the Necrobinder?
Torii (reduce small damage to 1) is exceptional because Osty absorbs big hits while Torii minimizes the small ones that get through. Dead Branch generates cards from Ethereal exhausts. Pen Nib doubles Doom-applying damage. Meat on the Bone triggers frequently at 66 HP. Self-Forming Clay provides supplemental Block when chip damage lands.
Quick Facts
- Tier
- B
- Difficulty
- Expert
- Starting HP
- 66
- Starting Relic
- Bound Phylactery
- Total Cards
- 88
- Total Builds
- 4
- Unlock
- Play a run as the Regent.
