On a Knife's Edge
Eternal, Pinned
Ceremonial Dagger (When [[Blinds|{{hl|orange|Blind}}]] is selected, destroy [[Jokers|Joker]] to the right and permanently add {{hl|orange|double}} its sell value to this {{hl|red|Mult}} <br> {{currently|{{mult|+0}}}} Uncommon Additive Mult Independent Ceremonial Dagger.png)The Pinned Joker is always in the leftmost position
On a Knife's Edge is a Challenge Deck. It features an Eternal Ceremonial Dagger (When [[Blinds|{{hl|orange|Blind}}]] is selected, destroy [[Jokers|Joker]] to the right and permanently add {{hl|orange|double}} its sell value to this {{hl|red|Mult}} <br> {{currently|{{mult|+0}}}} Uncommon Additive Mult Independent Ceremonial Dagger.png) with the unique "Pinned" quality, ensuring it cannot be moved from the leftmost position.
Starting Contents
The starting deck contains the standard 52 cards.
Synergies
A continuous source of income is important to keep feeding the Dagger, and because it can't be moved, players are forced to always have at least one disposable Joker while using the remaining three Joker slots for scoring Jokers.
Egg (Gains {{Money|3}} of {{Hl|orange|sell value}} at end of round Common Economy N/A (Passive) Egg.png) is incredibly useful to scale Ceremonial Dagger. However, players need to sacrifice yet another Joker slot to scale Egg in the process.
Riff-Raff (When [[Blind|{{hl|orange|Blind}}]] is selected, create {{hl|orange|2}} [[Common Jokers|{{hl|blue|Common}} {{hl|orange|Jokers}}]] <br> {{room}} Common Effect On Blind Select Riff-Raff.png) can provide disposable Jokers to feed the dagger. Make sure to keep a disposable Joker in between them so Riff-Raff can be kept after selecting a blind.
Joker Stencil ({{xmult|1}} for each empty [[Jokers|{{hl|orange|Joker}}]] slot <br> <small>Joker Stencil included</small> <br> {{Currently|{{xmult|1|}}}} Uncommon Multiplicative Mult Independent Joker Stencil.png) consistently provides at least X2 Mult upon selecting a Blind since Ceremonial Dagger destroys one Joker and thus creates an empty Joker slot.
Anti-Synergies
- Using
Invisible Joker (After {{hl|orange|2}} rounds, sell this card to {{hl|orange|Duplicate}} a random Joker <br> {{currently|{{hl|orange|0}}/2}} <br> {{hl|gray|(Removes [[Negative|{{hl|edition|Negative}}]] from copy)}} Win a run without ever having more than {{hl|orange|4 Jokers}} Rare Effect N/A (Passive) Invisible Joker.png) and 
Ankh (Create a copy of a random [[Jokers|{{hl|orange|Joker}}]], destroy all other Jokers <br> {{hl|gray|(Removes {{hl|edition|Negative}} from copy)}} Available from start. Spectral Ankh.png) carries a high risk as if it duplicates Ceremonial Dagger, the second copy will also be pinned, leaving the first one impossible to scale.
- While they can still be useful, note that
Brainstorm (Copies the ability of leftmost [[Jokers|{{hl|orange|Joker}}]] Discard a {{ph|Royal Flush}}. Rare Effect Brainstorm.png) is only able to copy Ceremonial Dagger, and 
Blueprint (Copies ability of [[Jokers|{{Hl|orange|Joker}}]] to the right Win a run Rare Effect Blueprint.png) cannot copy Ceremonial Dagger (unless it is copying Brainstorm), which limits their utility in this challenge.
- Be careful when facing
Verdant Leaf ( Showdown Verdant Leaf.png). If you rely on enhanced cards to score, you'll have to sell another Joker in addition to feeding Ceremonial one, leaving you with only three Jokers to beat this boss blind.
Clearance Sale (All cards and packs in shop are {{hl|orange|25%}} off Base Clearance Sale.png) and 
Liquidation (All cards and packs in shop are {{hl|orange|50%}} off Redeem at least 10 Voucher cards in one run Upgraded Liquidation.png) reduce the sell price of Jokers, so the + Mult gained for Ceremonial Dagger will be reduced as well.
In other languages
| Language | Name | Notes |
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| Chinese (Simplified) | 刀锋之上 | |
| Chinese (Traditional) | 刀鋒之上 | |
| Dutch | Bloedstollend | Literally 'Bloodcurdling'. Does not refer to a knife. |
| French | Sur le fil du rasoir | |
| German | Auf Messers Schneide | |
| Indonesian | Di Mata Pisau | |
| Italian | Sul filo del rasoio | |
| Japanese | 紙一重 | |
| Korean | 칼끝에서 | |
| Polish | Na ostrzu noża | |
| Portuguese (Brazilian) | No Fio da Navalha | |
| Russian | На острие ножа | |
| Spanish (Spain) | Al filo de la navaja | |
| Spanish (Latin America) | Al filo de la navaja | |
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| Standard Decks |
 Red Deck ( {{hl|red|+1}} discard every round Unlocked from start Red Deck.png) Blue Deck ( {{hl|blue|+1}} hand every round Discover at least {{hl|orange|20}} items from your [[collection]] Blue Deck.png) Yellow Deck ( Start with extra {{Money|10}} Discover at least {{hl|orange|50}} items from your [[Collection|collection]] Yellow Deck.png) Green Deck ( At end of each Round: <br> {{Money|2}} per remaining {{hl|blue|Hand}} <br> {{Money|1}} per remaining {{hl|red|Discard}} <br> Earn no {{hl|orange|Interest}} Discover at least {{hl|orange|75}} items from your [[collection]] Green Deck.png) Black Deck ( {{hl|orange|+1}} Joker slot <br> {{hl|blue|-1}} hand every round Discover at least {{hl|orange|100}} items from your [[collection]] Black Deck.png) Magic Deck ( Start run with the {{V|Crystal Ball|class=hl-purple}} voucher and {{hl|orange|2}} copies of {{tarot|The Fool}} Win a run with the {{D|Red}} on [[Stakes|any difficulty]] Magic Deck.png) Nebula Deck ( Start run with the {{V|Telescope|class=hl-cyan}} voucher <br> {{hl|red|-1}} consumable slot Win a run with the {{D|Blue}} on [[Stakes|any difficulty]] Nebula Deck.png) Ghost Deck ( [[Spectral Cards|{{hl|sblue|Spectral}}]] cards may appear in the shop, start with a {{spectral|Hex}} card Win a run with the {{D|Yellow}} on [[Stakes|any difficulty]] Ghost Deck.png) Abandoned Deck ( Start run with no {{F|}}[[Card Ranks#Face cards|{{hl|orange|Face Cards}}]] in your deck Win a run with the {{D|Green}} on [[Stakes|any difficulty]] Abandoned Deck.png) Checkered Deck ( Start run with {{hl|orange|26}} {{suit|Spades}} and {{hl|orange|26}} {{suit|Hearts}} in deck Win a run with the {{D|Black}} on any difficulty Checkered Deck.png) Zodiac Deck ( Start run with {{V|Tarot Merchant|class=hl-purple}}, {{V|Planet Merchant|class=hl-cyan}}, and {{V|Overstock|class=hl-orange}} Win a run with any [[Decks|deck]] on the {{Stake|Red}} difficulty or harder Zodiac Deck.png) Painted Deck ( {{hl|orange|+2}} hand size, <br> {{hl|red|-1}} Joker slot Win a run with any [[Decks|deck]] on the {{Stake|Green}} difficulty or harder Painted Deck.png) Anaglyph Deck ( After defeating each [[Blinds|{{hl|orange|Boss Blind}}]], gain a [[File:Double tag.png|24px]] [[Tags|{{hl|orange|Double Tag}}]] Win a run with any [[Decks|deck]] on the {{Stake|Black}} difficulty or harder Anaglyph Deck.png) Plasma Deck ( Balance [[Chips|{{hl|blue|Chips}}]] and [[Mult|{{hl|red|Mult}}]] when calculating score for played hand <br> {{hl|red|X2}} base Blind size Win a run with any [[Decks|deck]] on the {{Stake|Blue}} difficulty or harder Plasma Deck.png) Erratic Deck ( All [[Card Ranks|{{hl|orange|Ranks}}]] and [[Suits|{{hl|orange|Suits}}]] in deck are randomized Win a run with any [[Decks|deck]] on the {{Stake|Orange}} difficulty or harder Erratic Deck.png)
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| Challenge Decks |
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