Library Of Ruina is Project Moon's 2021 deck battler, where you run a Library that mails out invitations, fights the Guests who accept, and turns the losers into Books. Every librarian is defined by one Key Page, which fixes HP, Stagger Resist, Speed and the Slash, Pierce and Blunt resistance columns, plus a deck of exactly 9 Combat Pages. Fights resolve as clashes: both sides roll dice at each other, the higher roll wins and the loser's die is destroyed, so damage is something you win rather than something you spend. Books drop the pages that build the next deck, which means the difficulty curve is assembled out of whatever you beat last.
Picking the right build determines how your experience plays out. These builds are ranked by overall effectiveness, factoring in damage, survivability, gear requirements, and how well they scale into endgame. New to the game? Start with our beginner's guide first.
Quick Rankings
| Build | Tier | Playstyle | Core Gear |
|---|---|---|---|
| Floor of General Works | A | Balanced | Best available |
| Floor of History | A | Balanced | Best available |
| Floor of Technological Sciences | A | Balanced | Best available |
| Floor of Literature | A | Balanced | Best available |
| Floor of Art | A | Balanced | Best available |
For detailed meta rankings, see our Library Of Ruina tier list.
A-Tier: Floor of General Works
Floor of General Works is a top-performing option in Library Of Ruina.
Core Setup
| Slot | Choice | Why |
|---|---|---|
| Primary Equipment | Slash dice | One of the three offensive damage types, and the one most Bleed pages are attached to. |
| Core Gear | Best available for your level | Maximizes build potential |
| Stat Priority | Balanced offensive and defensive stats | Optimal scaling |
| Key Mechanic | Clashes and speed dice | At the start of each scene every character rolls speed dice, and those results set both turn order and who can be targeted. |
How to Play Floor of General Works
Floor of General Works focuses on a balanced approach to content.
Why this build works: Slash dice does the damage and Clashes and speed dice keeps it running, which is why this sits at the top of the list. See our weapons guide for detailed equipment breakdowns.
Pros:
- Highest overall performance
- Straightforward gearing path
- Works in all content types
Cons:
- Popular pick, resources may be contested
- Needs specific gear to reach full potential
A-Tier: Floor of History
Floor of History is a strong option in Library Of Ruina.
Core Setup
| Slot | Choice | Why |
|---|---|---|
| Primary Equipment | Pierce dice | The second offensive type, tracked on its own resistance row for both HP and stagger. |
| Core Gear | Best available for your level | Maximizes build potential |
| Stat Priority | Balanced offensive and defensive stats | Optimal scaling |
| Key Mechanic | Light and page cost | Light pays for Combat Pages. |
How to Play Floor of History
Floor of History focuses on a balanced approach to content.
Why this build works: Pair Pierce dice with Light and page cost and the build stops depending on a good start, so it holds up across most content. See our weapons guide for detailed equipment breakdowns.
Pros:
- Most versatile option
- Straightforward gearing path
- Works in all content types
Cons:
- Lower peak damage than S-tier
- Needs specific gear to reach full potential
A-Tier: Floor of Technological Sciences
Floor of Technological Sciences is a strong option in Library Of Ruina.
Core Setup
| Slot | Choice | Why |
|---|---|---|
| Primary Equipment | Blunt dice | The third offensive type. |
| Core Gear | Best available for your level | Maximizes build potential |
| Stat Priority | Balanced offensive and defensive stats | Optimal scaling |
| Key Mechanic | Stagger Resist and damage types | Every hit reduces HP and Stagger Resist on separate tracks with separate resistance tables. |
How to Play Floor of Technological Sciences
Floor of Technological Sciences focuses on a balanced approach to content.
Why this build works: Stagger Resist and damage types covers the gap Blunt dice leaves open, so the build stays usable even when a fight goes badly. See our weapons guide for detailed equipment breakdowns.
Pros:
- Best survivability
- Straightforward gearing path
- Works in all content types
Cons:
- Slower clear speeds
- Needs specific gear to reach full potential
A-Tier: Floor of Literature
Floor of Literature is a specialized option in Library Of Ruina.
Core Setup
| Slot | Choice | Why |
|---|---|---|
| Primary Equipment | A Zwei Fixer's Page | An Urban Legend rank Key Page, sitting in the same tier as A Stray Dog's Page and the Grade 8 Fixer pages. |
| Core Gear | Best available for your level | Maximizes build potential |
| Stat Priority | Balanced offensive and defensive stats | Optimal scaling |
| Key Mechanic | Emotion Level | Emotion starts at 0 in a Reception and climbs to a cap set by Floor level for librarians and chapter rank for guests, up to 5. |
How to Play Floor of Literature
Floor of Literature focuses on a balanced approach to content.
Why this build works: This one leans on Emotion Level rather than raw numbers, and A Zwei Fixer's Page is what makes that trade pay off. See our weapons guide for detailed equipment breakdowns.
Pros:
- Strong in group/team content
- Straightforward gearing path
- Excels in its niche
Cons:
- Weaker solo performance
- Requires deep game knowledge
A-Tier: Floor of Art
Floor of Art is a specialized option in Library Of Ruina.
Core Setup
| Slot | Choice | Why |
|---|---|---|
| Primary Equipment | A Grade 7 Fixer, Page 1 | One rung above the Grade 8 Fixer pages, on the City's fixer scale where Grade 9 is the bottom and Grade 1 the top. |
| Core Gear | Best available for your level | Maximizes build potential |
| Stat Priority | Balanced offensive and defensive stats | Optimal scaling |
| Key Mechanic | Books and Reception invitations | Beating a guest drops their Book, which you burn at the desk for Key Pages and Combat Pages. |
How to Play Floor of Art
Floor of Art focuses on a balanced approach to content.
Why this build works: A Grade 7 Fixer, Page 1 and Books and Reception invitations pull in the same direction here, which separates this from the safer picks above. See our weapons guide for detailed equipment breakdowns.
Pros:
- Unique, rewarding playstyle
- Straightforward gearing path
- Excels in its niche
Cons:
- High skill floor, punishing when misplayed
- Requires deep game knowledge
Build Progression Path
- Start with Floor of History: the most forgiving option for learning the game
- Transition to Floor of General Works once you understand core mechanics and have access to Slash dice
- Keep a Floor of Technological Sciences setup for content that keeps killing you
- Try Floor of Art for a fresh experience once you've mastered the basics
Follow our walkthrough for the optimal progression path through each area.
Gearing Tips
- Invest in your primary equipment first, since it gives the biggest power spike. See our weapons guide for rankings.
- Open the guest's Key Page before you build. The Slash, Pierce and Blunt columns run Ineffective 0.25x, Endured 0.5x, Normal 1x, Weak 1.5x and Fatal 2x, and the stagger table is separate from the HP table, so a fight can be won on stagger with damage types that barely scratch health.
- Redirecting is free and it is the strongest button in the game. Pointing a librarian at whichever enemy die would otherwise hit unopposed converts a one-sided attack into a clash, and a clash you lose still destroys nothing except one die.
- Don't spread upgrade resources across multiple builds until endgame
More Library Of Ruina Guides
- Library Of Ruina Library Of Ruina Overview
- Library Of Ruina Tier List
- Library Of Ruina Walkthrough
- Library Of Ruina Beginner's Guide
- Library Of Ruina Tips & Tricks
- Library Of Ruina Weapons Guide
- Library Of Ruina Combat Guide
- Library Of Ruina Boss Guide
- Library Of Ruina Maps & Locations
- Library Of Ruina Crafting Guide
- Library Of Ruina Classes & Characters
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- Balatro Builds: card-game game with similar mechanics
- Sultan's Game Builds: card-game game with similar mechanics
