Osty

Pet
Ascension does not change its numbers
Health
1 HPAlways 1.
Gold
0 goldThis fight pays no gold.
Osty1/1Osty

Turn 1

How to beat Osty

Summoning Osty

  • Summon X: brings Osty out with X Max HP and X HP.
  • Already alive: the same keyword raises his Max HP by X instead.
  • Already dead: it revives him at X.
  • Bound Phylactery: summons 1 at the start of every turn.

Damage redirection

  • Die for You: any unblocked attack damage aimed at the Necrobinder goes to Osty's HP instead, after your own Block has soaked what it can.
  • Non-attack damage such as Burn still hits you.

Using him

  • He is both a shield and your damage: keep his HP topped up with repeated Summons.
  • Spend him with cards like Bone Shards or Sacrifice when that is worth more than keeping him.

Notes

  • When Osty dies he stays on the field with a hidden health bar until the next Summon, which is why re-summoning is cheap.
  • Powers cannot be applied to him while dead.
  • Enemy multi-hit attacks are dangerous for him, since every unblocked hit is redirected.
  • He is listed among monsters because the game builds him from the same creature model.

From the code

Osty is the Necrobinder's companion, not an enemy: Bound Phylactery summons him at the start of your turn, he has no move of his own and only attacks when one of your cards tells him to.

Changes by version

  1. Buffed Sacrifice card: Block gain increased from double to triple Osty's Max HP
  2. 16 Jul 2026Bug fixPlaytest
    Fixed awkward delay when Osty and Kaiser Krab would spawn at start of combat
  3. Buffed The Boot relic: damage increase now also applies to Osty's attacks
    Bug fixv0.107.1
    Fixed a crash when Osty dies during a scene transition
All 70 patch notes67 older
  1. 4 Jun 2026BuffThe BootBeta branch
    Buffed The Boot relic: damage increase now also applies to Osty's attacks
  2. 26 Apr 2026Bug fixBeta branch
    Fixed crash when Osty dies during scene transition
  3. 9 Apr 2026ArtBeta branch
    Updated art for Osty in character select screen
  4. 2 Apr 2026TextFoul PotionBeta branch
    Foul Potion description now specifies that it deals damage to "ALL players and enemies" instead of "EVERYONE", making it clearer that it does not hit Osty
  5. 26 Mar 2026Bug fixFoul PotionBeta branch
    Foul potion no longer damages Osty
  6. 26 Feb 2026Bug fixMelancholyInternal playtest
    Fixed an issue where Melancholy card's cost reduction would persist between combats if the reduction was due to Osty dying
  7. 5 Feb 2026ChangeThornsInternal playtest
    Osty now uses the player's block when he is dealt damage directly (for example, when using an Osty attack on an enemy with Thorns)
    TextReaper FormLethalityInternal playtest
    Reaper Form and Lethality card wording changed to imply Osty attacks also benefit
    Bug fixPhylactery UnboundInternal playtest
    Fixed a visual issue with Phylactery Unbound relic where Osty wouldn't appear until after you'd drawn your opening hand
  8. 29 Jan 2026TextHigh FiveVulnerableInternal playtest
    High Five card is now clearer that Vulnerable is not applied if Osty is dead
  9. 22 Jan 2026SoundInternal playtest
    Added Osty Summon SFX
  10. 15 Jan 2026Bug fixByrdpipSurroundedInternal playtest
    Osty, Byrdpip, and other pets now properly turn around when you attack the enemy behind you in a Surrounded encounter
  11. 8 Jan 2026UpgradeInternal playtest
    Upgrade no longer based on Osty's max HP; stays based on Osty's current HP
    Bug fixThe NecrobinderSic 'EmInternal playtest
    Necrobinder's Sic 'Em card no longer Summons for other players when their Osty hits the target in multiplayer
  12. 1 Jan 2026BuffCalcifyInternal playtest
    Buffed Calcify card: Osty's bonus damage increased from 3(4) to 5(7)
    Bug fixInternal playtest
    Fixed Sic'Em crashing when played without Osty
    Bug fixInternal playtest
    Fixed hitching when Osty revives
  13. 18 Dec 2025Bug fixInternal playtest
    Sic'Em Power triggers Summon when Osty hits the target
  14. 4 Dec 2025TextHigh FiveInternal playtest
    While common sense dictates that you can't high-five a dead Osty, we've nevertheless updated High Five card's wording to specify that it can only be played if Osty is alive
    Bug fixStrengthWeakSqueezeInternal playtest
    Fixed an issue where, if the player had damage-modifying powers like Strength or Weak, they modified the Osty damage values displayed in Squeeze card's description even though the damage that was actually dealt was correct
  15. 23 Oct 2025Bug fixFlattenStrengthInternal playtest
    Flatten card now properly displays the extra damage that will be dealt by Osty's Strength
  16. 25 Sep 2025InterfaceInvokeInternal playtest
    Invoke card now glows gold if Osty has attacked this turn
    Fossil Stalker and Infested Prism monsters' Suck power no longer double-dips on Strength gain when a hit kills Osty and "tramples" over to also hit the player
  17. 18 Sep 2025Bug fixMystic LighterInternal playtest
    Mystic Lighter relic now properly increases the damage of Osty attack cards
  18. 4 Sep 2025Bug fixInvokeInternal playtest
    If Invoke card is Transfigured and then Osty attacks, Invoke now properly costs 0 instead of 1
  19. 21 Aug 2025Bug fixBufferInternal playtest
    Buffer power no longer prevents Osty from losing HP
    Bug fixTungsten RodInternal playtest
    Tungsten Rod relic no longer prevents Osty from losing HP
  20. 14 Aug 2025Bug fixInternal playtest
    The Formula potion now properly applies to Osty attack cards
  21. 7 Aug 2025BuffInternal playtest
    Buffed Empower card: now also says "Osty no longer loses Buffs on Death"
    Bug fixInternal playtest
    Osty attacks no longer glow red when combat ends
    Bug fixInternal playtest
    Single-target Osty attack cards no longer hit all enemies
    Bug fixInternal playtest
    Heart Piece relic now properly excludes damage dealt to Osty from its 20-damage-per-turn threshold
  22. 24 Jul 2025DamageThe NecrobinderInternal playtest
    Changed Make Use card: Osty now attacks and deals the damage instead of Necrobinder
    Bug fixLethalityInternal playtest
    Lethality card's extra damage is now properly previewed on Osty attack cards when Osty is dead
  23. 17 Jul 2025Bug fixRattleInternal playtest
    Rattle card now properly glows red if Osty is dead
    Bug fixSkittishInternal playtest
    Phantasmal Gardeners' Skittish power now activates on Osty attacks
  24. 10 Jul 2025InterfaceDoomInternal playtest
    When Necro dies to Doom, Osty dies as well
    Bug fixSandpitInternal playtest
    Fixed various visual issues with Osty and Sandpit
    Bug fixHand DrillInternal playtest
    Hand Drill relic is now properly triggered when Osty breaks an enemy's block
    Bug fixInternal playtest
    Osty now actually shakes when you play an Osty attack while it's dead
    Bug fixInternal playtest
    Osty is no longer summoned by dead players' Bound Phylacteries
  25. 3 Jul 2025InterfaceInternal playtest
    Osty's attack cards now glow red if Osty is dead
  26. 26 Jun 2025InterfaceInternal playtest
    Osty now shakes if you try to play an Osty attack while he's dead
  27. 20 Jun 2025InterfaceInvokeInternal playtest
    Invoke card now glows gold if Osty is dead
    InterfaceInternal playtest
    Adjusted intent position, hitbox size, and center for Osty
  28. 8 May 2025Bug fixFossil StalkerStrengthInternal playtest
    Fossil Stalker now properly gains Strength when dealing unblocked attack damage to Osty
  29. 25 Apr 2025Bug fixThieving HopperInternal playtest
    Health bars no longer show orange when the HP bar size changes (ex. at the start of a multiplayer session, when Osty changes size, when the Thieving Hopper starts flying)
    Bug fixInternal playtest
    Tide's Binding relic no longer prevents Osty from healing (or other players in multiplayer)
  30. 10 Apr 2025ArtThe NecrobinderInternal playtest
    Randomized Necrobinder & Osty's fire a small amount at the rest site
    Bug fixThe NecrobinderInternal playtest
    Osty is now placed correctly at the rest site when Necrobinder is on the far side of the log (no more sitting on Osty)
  31. 3 Apr 2025InterfaceInternal playtest
    Damage numbers on Osty no longer show overkill damage
  32. 13 Mar 2025Bug fixInternal playtest
    Osty no longer layers over byrdpip in game over screen
  33. 7 Mar 2025Bug fixCorpse SlugRavenousInternal playtest
    Corpse Slug's Ravenous no longer procs when Osty dies
  34. 27 Feb 2025InterfaceInternal playtest
    Osty now grows in size as he gains more max HP
    Bug fixShared FateInternal playtest
    Fixed an issue where playing Shared Fate card would cause a softlock if Osty was dead
  35. Changed Sentry Mode card: the damage that Osty deals via this card now counts as attack damage, meaning effects like Strength and Vigor now apply to it
    InterfaceThe NecrobinderInternal playtest
    Osty's healthbar now shows the blue block outline when Necrobinder has block
    InterfaceInternal playtest
    Remote players' Osty is no longer hoverable
    Bug fixSwipeInternal playtest
    Fixed softlock that occurred when playing Swipe card while Osty is dead
    Bug fixThornsInternal playtest
    Osty now properly plays his death animation when he dies to Thorns during a multi-hit attack
    Bug fixSoul NexusInternal playtest
    Fixed an issue where Soul Nexus's Soul Wither power would decrement when one of its attacks damaged Osty but not the player
  36. 13 Feb 2025ChangeLethalityInternal playtest
    Changed Lethality card: now applies to Osty's attacks in addition to yours
  37. 6 Feb 2025Bug fixInternal playtest
    Remote player's Osty's healthbar no longer reappears when it revives
  38. 30 Jan 2025Bug fixInternal playtest
    Fixed an issue with Unending Service card enchanted with Momentum while Osty is dead not previewing Momentum's extra damage
  39. 16 Jan 2025Bug fixSlipperyFriendshipInternal playtest
    Fixed an issue where the Slippery power was preventing damage from Osty's Friendship attack in addition to the attack card that triggered it
  40. 9 Jan 2025InterfaceInternal playtest
    Empower card now shows targeting reticle over Osty
  41. 5 Dec 2024ArtInternal playtest
    Osty's body now remains in combat after dying, and plays a revive animation when re-summoned
    TextSacrificeInternal playtest
    Sacrifice card now specifies that it only works if Osty is alive
    Bug fixThe NecrobinderStrengthInternal playtest
    Damage amounts on Osty attack cards no longer reflect Necrobinder's Strength when Osty is dead
  42. 21 Nov 2024BuffInternal playtest
    Buffed Transfuse card: Osty healed HP increased from 10(15) to 15(20)
    ArtInternal playtest
    Animated rest site Osty to be a left hand
  43. 14 Nov 2024MentionInternal playtest
    "Summon 5(7). Osty deals 5(7) damage."
    MentionInternal playtest
    Reworked Milk potion: "Heal Osty for 25 HP."
    DamageInternal playtest
    "Osty deals 5 damage twice (3 times)."
    ChangeExhaustInternal playtest
    "Osty heals 10(15) HP. Exhaust."
    ChangeSentry ModeStrengthVigorInternal playtest
    Changed Sentry Mode card: Osty's attacks no longer benefit from Strength or Vigor
    ArtInternal playtest
    Osty now pokes the enemy instead of slamming them for some cards
    Bug fixThe NecrobinderInternal playtest
    Necrobinder no longer plays death animation twice if she is killed at the same time as Osty
    Bug fixThe NecrobinderInternal playtest
    Necrobinder now plays SFX and VFX when Block is hit, even if Osty is out
    Bug fixThe NecrobinderThe InsatiableInternal playtest
    Osty and Necrobinder are now both properly pulled towards The Insatiable
  44. 7 Nov 2024Bug fixBone ShardsInternal playtest
    Damage from Bone Shards card is now properly dealt by Osty instead of the player
    Bug fixThe NecrobinderInternal playtest
    Damage VFX no longer plays on Necrobinder when Osty absorbs all damage from an attack
    Bug fixInternal playtest
    Fixed an issue with the Plague Carrier card where its effect was wearing off if Osty died and was resummoned
    Bug fixInternal playtest
    Osty no longer gains extra HP in Burly monster rooms
    Bug fixInternal playtest
    Osty's health no longer occasionally shows up in the top bar HP counter when playing as the Necrobinder
    Bug fixInternal playtest
    Sharp enchantment now displays its damage bonus on Osty attack cards even when Osty is dead
    Bug fixVantomInternal playtest
    Vantom attacking Osty no longer causes a softlock
  45. 1 Nov 2024AddedInternal playtest
    Added to the game
    RemovedInternal playtest
    Deprecated Osty's Devotion relic
    ChangeStrengthVigorSentry ModeInternal playtest
    Osty's Strength/Vigor now applies to his Sentry Mode attacks
    ChangeSentry ModeInternal playtest
    Sentry Mode power is now applied to the player, meaning it can be played while Osty is dead and it will still trigger after he's summoned
  46. 12 Jul 2024Bug fixPlatingThe NecrobinderInternal playtest
    Chain Mail Pants card now applies Plating to Osty, not Necrobinder
    Bug fixSlippery BridgeInternal playtest
    Osty now loses HP first at Slippery Bridge event
  47. 14 Jun 2024Bug fixRegenInternal playtest
    Regen is no longer proc'd on Osty if he is dead
    Bug fixInternal playtest
    Targeting reticle is no longer shown when targeting an attack on Osty
    Bug fixHexSpectral KnightInternal playtest
    Fixed softlock when Hex is applied to Osty by Spectral Knight
  48. 7 Jun 2024Bug fixThe NecrobinderInternal playtest
    Lightning orbs no longer hit Necrobinder if Osty is alive
  49. 24 May 2024MentionDoomInternal playtest
    Reworked Fearmonger card: "Whenever YOU attack an enemy with Doom, Osty gains 6(9) Block."
    DamageInternal playtest
    "Osty deals 30(40) damage to ALL enemies."
  50. 17 May 2024Bug fixInternal playtest
    Toothed enchantment now properly targets Osty instead of Necro
  51. 10 May 2024Bug fixInternal playtest
    Run history now reflects damage taken by Osty
    Bug fixPlatingInternal playtest
    Plating on Osty no longers procs if Osty is dead
    Bug fixInternal playtest
    Bedlam Beacon event now uses Osty max HP for its HP loss threshold
    Bug fixInternal playtest
    Bird Faced Urn relic now heals Osty instead of Necro
    Bug fixInternal playtest
    Block gained from Despair now prioritizes Osty
    Bug fixSoulThe NecrobinderInternal playtest
    Soul Buddy relic now applies health gain to Osty instead of Necrobinder
    Bug fixVulnerableInternal playtest
    Vulnerable on Osty is now reflected in then enemy intent damage preview
    Bug fixVulnerableWeakInternal playtest
    Vulnerable/Weak no longer ticks down on the first turn it's applied to Osty
  52. Necrobinder now starts with two relics: Osty's Devotion and Bound Phylactery
    Related relicBound PhylacteryInternal playtest
    Bound Phylactery: "At the end of combat, heal ALL HP. If Osty is dead, revive him with 1 HP."
    BlockInternal playtest
    Osty's Devotion: now "All enemy Attacks and Debuffs target Osty. All Block is gained by Osty."
    ChangeThe NecrobinderInternal playtest
    Necrobinder can no longer swap places with Osty
    DamageExhaustInternal playtest
    "Osty deals 5 damage 3(4) times. Exhaust."
    MentionInternal playtest
    "Lose 2 HP. Whenever Osty attacks, he hits an additional time."
    DamageInternal playtest
    Osty deals 10(15) damage to ALL enemies
    MentionInternal playtest
    "Lose 1 HP. Osty deals 1(2) damage 5 times."
    ChangeStrengthInternal playtest
    "Osty loses 1 Strength. YOU gain 2(3) Strength."
    ChangeInternal playtest
    "Osty deals 5 damage twice. Gain 5(10) Block."
    MentionRetainInternal playtest
    "Retain. Osty deals 5 damage for each Skill already played this turn."
    DamageDoomExhaustInternal playtest
    "Osty deals 5 damage. Apply 15(20) Doom. Exhaust."
    MentionInternal playtest
    "The first time you and Osty attack the same enemy each turn, gain 3 energy."
    ChangeInternal playtest
    Osty's max HP increased from 45 to 55
    MentionRetainStrengthDexterityInternal playtest
    "(Retain) Lose 1 HP. Osty gains 1 Strength. Osty gains 1 Dexterity."
    MentionVigorInternal playtest
    "Gain 12(16) Block. Osty gains 4(6) Vigor."
    MentionInnateVigorStrengthInternal playtest
    "Innate. Whenever Osty gains Vigor or Strength, YOU also gain that much."
    MentionPlatingInternal playtest
    "Lose 1 HP. Osty gains 10 Plating."
    BuffThornsInternal playtest
    Buffed Barbs+: Thorns granted to Osty changed from 6 to 7
    MentionVigorInternal playtest
    Changed Loyalty: now "Lose 2(1) HP. Gain 5(6) Block. Osty gains 5(6) Vigor."
    DamagePull AggroInternal playtest
    Changed Pull Aggro: now "Osty deals 5 damage twice(three times)."
    MentionInternal playtest
    Reworked Heel: "Gain 5(6) Block. Gain 5(6) additional Block for every time Osty attacked this turn."
    MentionDoomInternal playtest
    Reworked Plague Carrier: now "Whenever Osty attacks an enemy, apply 3(4) Doom to them."
    Related cardReanimateExhaustInternal playtest
    Reworked Reanimate: now "Lose 2 MAX HP. Revive Osty and he heals 55 HP. Exhaust."
    ReworkSacrificeExhaustInternal playtest
    Reworked Sacrifice: now "Osty loses 5 HP. You heal to full HP. Exhaust."
    ReworkWeakInternal playtest
    Reworked Slap: now "Osty deals 5 damage and applies 2(3) Weak."
    ReworkVulnerableInternal playtest
    Reworked Tackle: now "Osty deals 5 damage and applies 2(3) Vulnerable."
    InterfaceInternal playtest
    Osty's health now appears in the top bar when playing as the Necrobinder
    Bug fixInternal playtest
    Multihit on killing Osty no longer breaks his animations
    Bug fixBound PhylacteryInternal playtest
    Bound Phylactery now heals Osty to 1 HP if he is dead
  53. 26 Apr 2024Bug fixPen NibInternal playtest
    Pen nib now correctly doubles Osty's damage
  54. 19 Apr 2024Bug fixSentry ModeInternal playtest
    The Sentry Mode power no longer triggers when Osty dies
  55. 15 Sep 2023ChangeReanimateInternal playtest
    Reanimate now costs 3 and no longer heals Osty to full on upgrade
    Bug fixVulnerableInternal playtest
    Enemy intent damage now reflects Vulnerable on Osty if he is in front
    Bug fixPen NibInternal playtest
    Osty now properly benefits from Pen Nib
    Bug fixInternal playtest
    The text in Osty-attack cards now properly reflects Osty's damage-modifying powers, and the text in block cards now properly reflects the block-modifying powers of whichever creature is in front
    Bug fixInternal playtest
    Osty now correctly stays dead on save and reload
    Bug fixInternal playtest
    Fixed softlock if the Necrobinder dies before Osty
    Bug fixInternal playtest
    Fixed Osty switch button not showing up when Osty revives
    TextInternal playtest
    The description for the Osty's Devotion relic has been updated for greater clarity
  56. 8 Sep 2023ChangeInternal playtest
    You and Osty each gain 5(8) Shield
    MentionStrengthVigorInternal playtest
    "If Osty is dead, revive him and apply 5(8) Strength." to "Transfer all your Vigor to Osty. Draw 1 card."
    BlockDexterityInternal playtest
    "Osty gains 3(4) Dexterity." to "Osty gains 12(16) Block and moves to the front. You can't swap this turn."
    MentionVigorInternal playtest
    "If Osty is dead, deal 11(16) damage." to "You and Osty each gain 3(4) Vigor."
    BlockInternal playtest
    "Osty gains 15(20) Block." to "Osty gains 8(11) Shield."
    DamageDoomExhaustInternal playtest
    "Osty heals HP equal to the amount of Doom on ALL enemies." to "Osty deals 18(24) damage. If this kills an enemy, gain 3 energy. Exhaust."
    DamageInternal playtest
    "Osty attacks 5 times." to "Osty deals 5(6) damage 5 times."
    MentionDoomInternal playtest
    "Whenever Osty dies, ALL enemies gain 20(25) Doom." to "Whenever Osty gains Block, apply 3(4) Doom to a random enemy."
    ChangeInternal playtest
    Increased Osty's HP from 15 to 45
    ChangeInternal playtest
    Enemy debuffs are now redirected to Osty if he's in front
    ChangeInternal playtest
    Osty no longer revives and heals at the start of every room. Instead, Osty can be revived and healed by resting at rest sites
    Bug fixInternal playtest
    Fearmonger power now triggers when "Osty deals damage" attacks are played
    InterfaceThe NecrobinderInternal playtest
    Added button for swapping between Necrobinder and Osty being "in front"
    Related cardSentry ModeInternal playtest
    Sentry Mode: "At end of turn, Osty attacks a random enemy for 10 damage." to "At the end of your turn, Osty deals 10 damage to a random enemy."
    TextInternal playtest
    Updated Osty's Devotion relic description
  57. 14 Jul 2023InterfaceInternal playtest
    Osty's corpse now wiggles if you try to perform an action on him while he is dead
  58. 30 Jun 2023Bug fixThe NecrobinderInternal playtest
    Make attacks redirected to Osty show VFX on Osty instead of Necrobinder
    Bug fixInternal playtest
    Osty blocks admage taken in event rooms
  59. 16 Jun 2023DamageInternal playtest
    Osty no longer has intents or takes turns and redirects all damage to itself
    ReworkTag TeamInternal playtest
    Rework Tag Team card, damage is static as Osty no longer attacks
    Bug fixInternal playtest
    Osty not visible ressurecting at the end of combat
  60. 9 Jun 2023ChangeThe NecrobinderInternal playtest
    Osty and Necrobinder HP dramatically reduced
  61. 26 May 2023ChangeInternal playtest
    Osty no longer loses powers when dying
    InterfaceInternal playtest
    Show power hovertips while Osty is dead
  62. 19 May 2023ChangeThe NecrobinderInternal playtest
    We're looking into changing up Necrobinder but not quite yet. However, Osty now attacks the closest enemy so that's a big shift
    ChangeInternal playtest
    Osty now attacks the nearest enemy
  63. 5 May 2023ArtInternal playtest
    New Osty animations
    ArtInternal playtest
    Update Osty mix setting
    Bug fixInternal playtest
    Dragged Prey card was still dealing damage when Osty was dead
    Bug fixInternal playtest
    Osty is no longer in the shop rooms. No pets allowed
    Bug fixInternal playtest
    Osty was attacking dead Decemillipede segments
  64. 29 Apr 2023Bug fixInternal playtest
    Osty appearing in shop
    Bug fixInternal playtest
    Fix Osty intent disappearing after going to shop
  65. 21 Apr 2023ArtInternal playtest
    Implemented Osty animations
    ArtInternal playtest
    Minor change in Osty's size
    InterfaceSacrificeInternal playtest
    Update Sacrifice card from Destroy Osty to Kill Osty
    InterfaceSacrificeInternal playtest
    Update Sacrifice card wording again to imply Osty must be killed to gain energy
  66. 17 Feb 2023Bug fixInternal playtest
    Osty's name now appears in attack intents
  67. 9 Feb 2023DamageInternal playtest
    Cards that have Osty deal damage but not you are now Skills
    Bug fixInternal playtest
    Fix some issues around Osty's name

Internal playtest notes are from before the Early Access release. Names and numbers in them can differ from the game today.

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