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New character · Main v0.107.1 · Beta v0.111.0 notes

Necrobinder Guide

Osty is a shield, a battery and a weapon. Decide which one you need now.

Use Summon as stored value: it protects future turns and raises Unleash damage now. Draft immediate damage, Weak and a second defense tool before committing to Osty, Doom or Soul. A keyword is not a build until both its generator and payoff exist.

Necrobinder and Osty on the official Slay the Spire 2 character selection screen
Official character-select screenshot showing Necrobinder and Osty. Source: Mega Crit press kit
Base HP66
UnlockComplete a run with Regent
Starting relicBound PhylacterySummon 1 at the start of your turn.
Starting deck4 Strike, 4 Defend, 1 Bodyguard, 1 Unleash

Start with the engine

How Necrobinder actually wins

Osty takes Attack damage that gets through Block and can carry Summon value across turns. Unleash reads his current HP, while Protector and Sacrifice care about Max HP. That difference matters: an Osty who has just absorbed a hit may have a large ceiling but a weak Unleash right now.

Necrobinder naturally likes slower fights, but she still needs front-loaded damage and answers for non-Attack health loss. Doom, Souls and Ethereal cards are separate resource chains. Take them when the deck has both a way to produce the resource and a reason to spend it.

SummonOstySoulsDoomEthereal cards

Floor-one priorities

Act 1: draft answers, not a fantasy deck

  1. 01
    Solve the next enemy first

    Defile, Reave, Poke and Flatten are useful before any package exists. Overgrowth especially punishes a deck that only prepares for turn six.

  2. 02
    Find Weak or real Block

    Defy, Grave Warden and Negative Pulse reduce the pressure on Osty. A second Summon source matters when he is dying faster than Bound Phylactery rebuilds him.

  3. 03
    Let one card cover two holes

    Deathbringer supplies area Doom and Weak; Negative Pulse defends while setting up Doom. Compression keeps the first deck cycle functional.

  4. 04
    Require a build signal

    Haunt without Souls, Shroud without repeatable Doom and Calcify without enough Osty attacks are still isolated cards, not reasons to force a lane.

  5. 05
    Upgrade stability

    Bodyguard+ is a reliable default because more Summon means more defense and a stronger Unleash. Graveblast+ can become a cross-package recursion tool when the deck already supports it.

Three packages to recognize

Necrobinder builds that have a real game plan

Treat these as packages, not shopping lists. Move in when you already own the signal cards; keep taking standalone answers when the package has not shown up.

01
Commit signal · Extra Summon plus a premium Osty attack, Calcify, Bone Flute or Necro Mastery

Osty Summon

Grow the second health bar, spend it on attacks or a decisive Sacrifice, then rebuild it before the next hit.

Core cards
Bodyguard · Unleash · Afterlife · Invoke · Dirge · Reanimate
Support
Sic 'Em · Rattle · Squeeze · Defy · Graveblast
Relics
Bone Flute · Bookmark · Ivory Tile · Bag of Preparation

How a turn plays: Summon early, reduce incoming damage, and use Unleash while current HP is high. Play normal Osty attacks before Bone Shards or Sacrifice, then Summon again after spending him.

What breaks it: Treating Osty as ordinary Block. He does not cover most direct HP loss or status damage, and an empty Osty makes later Osty attacks do nothing.

02
Commit signal · Scourge, Deathbringer or No Escape plus a defense or payoff such as Death's Door or Shroud

Doom control

Use Weak and Block to buy time, push enemies over the Doom threshold, and bring scaling for bosses that outlive fixed Doom values.

Core cards
Scourge · Deathbringer · No Escape · Countdown · Reaper Form
Support
Negative Pulse · Death's Door · Shroud · Sleight of Flesh · Misery
Relics
Book Repair Knife · Undying Sigil · Unsettling Lamp · Bag of Preparation

How a turn plays: Strip Artifact with a cheap debuff, then commit the large Doom source. Keep defending after the threshold: normal Doom executes at the end of the enemy turn, not immediately.

What breaks it: Assuming a doomed enemy cannot attack. Without End of Days or enough Block, the deck can meet the kill threshold and still lose before the execution happens.

03
Commit signal · A Soul generator paired with Haunt, Devour Life, Death March or Soul Storm

Soul and Ethereal

Use generated Souls as free card flow, then turn their play and Exhaust history into damage, draw or an Ethereal replay turn.

Core cards
Reave · Grave Warden · Capture Spirit · Haunt · Soul Storm
Support
Devour Life · Death March · Spirit of Ash · Pagestorm · Eidolon
Relics
Funerary Mask · Big Hat · Ivory Tile · Bookmark

How a turn plays: Install the payoff before generating a large batch of Souls. In Beta, leave valuable Ethereal cards in hand when you want Eidolon to replay them from the Exhaust pile.

What breaks it: Generating Souls with no payoff. Free draw can still delay the real deck and creates little value when the fight punishes long, unfocused cycles.

Items worth changing your plan for

Recommended relics and why they fit

Bone Flute

Every Osty attack grants Block, connecting the starting Unleash to defense even outside a dedicated Summon deck.

It is only as reliable as the deck's ability to keep Osty alive.

Funerary Mask

Three starting Souls provide free card flow and immediate fuel for Soul and Exhaust payoffs.

Extra cycling is not a win condition without damage or defense attached.

Big Hat

Two random Ethereal cards can jump-start an Ethereal package and give Beta Eidolon material.

Random cards can be awkward; evaluate the actual hand, not the relic's best case.

Bookmark

Retained expensive cards such as Sacrifice or Reap can become affordable while waiting for the right turn.

The reduction hits a random retained card, so crowded Retain plans dilute it.

Unsettling Lamp

Doubling the first debuff source can create a decisive Doom or Weak opening.

Plan the first debuff carefully instead of spending it on a token application.

Execution wins close fights

How to pilot the deck cleanly

  • Think of Summon as a deposit. It can absorb a later Attack and raises current Osty HP for Unleash now.
  • Unleash reads current HP, not Max HP. Using it after Osty absorbed a large hit wastes much of the stored ceiling.
  • Play ordinary Osty attacks before a card that kills or spends Osty, then Summon again after the sacrifice.
  • Break Artifact with a cheaper debuff before Deathbringer or Scourge; Artifact cancels the whole Doom source, not one point.
  • Use Graveblast+ to retrieve the answer for this turn—Block, Doom, Soul generation or Energy—not automatically the biggest damage card.
  • For Beta Eidolon, an Ethereal card normally reaches the Exhaust pile only if it remains in hand at end of turn; playing it usually sends it to discard.

Common mistakes

  • Expecting Osty attacks to scale with Strength or be reduced by Weak. They use their own rules.
  • Treating Summon as normal Block. It changes Osty's current and combat Max HP and can later become damage or Sacrifice value.
  • Assuming Doom kills immediately when it reaches current HP. Normal Doom waits until the enemy turn ends.
  • Adding every Soul generator. Without a payoff, the extra cards complicate the cycle more than they solve the fight.
  • Assuming a played Ethereal card was Exhausted. Unless its text says so, playing it normally puts it in the discard pile.
  • Using Beta's triple Sacrifice value on Main. Main v0.107.1 still grants only double Osty Max HP as Block.

Current experimental branch

What Beta v0.111.0 changes for Necrobinder

Beta v0.111.0 keeps the higher Soul/Ethereal ceiling and triple Sacrifice value, while improving Shroud and making Time's Up repeatable. The Main branch still rewards the same basic discipline: solve damage and defense before drafting delayed payoffs.

EidolonNow plays every Ethereal card in the Exhaust pile, then Exhausts

It becomes a real replay payoff and can no longer be treated as the old hand-size Intangible card.

SacrificeBlock increases from twice to three times Osty's Max HP

A developed Osty can become a much stronger emergency or boss-turn defense, though rebuilding him still matters.

Soul StormScaling rises from 2(3) to 4(6) per exhausted Soul

A Soul engine gains a credible finisher instead of only card flow.

The ScythePermanent growth rises from 4(5) to 5(7)

The single-card long-run investment reaches useful damage faster.

Shroud / Time's UpShroud gains 3(4) Block instead of 2(3); Time's Up no longer Exhausts

Necrobinder gets a stronger defensive card and a more repeatable Ethereal payoff in the latest beta.

Go one layer deeper

Related mechanics in the database