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.
Combat in Library Of Ruina rewards knowledge over reflexes. Understanding how each mechanic works (and how they interact) is what turns a struggling player into a dominant one. New here? Start with our beginner's guide for the basics.
Core Combat Mechanics
1. 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. When two characters point at each other their dice clash one pair at a time, higher roll wins, and the loser's die is destroyed without dealing damage. If nobody redirected onto you, the attack is one-sided and lands every die in full, which is why a scene where you win the speed roll and a scene where you lose it are two different fights.
Why it matters: This is the foundation of all combat. Everything else builds on this.
2. Light and page cost
Light pays for Combat Pages. Characters start a Reception at maximum Light, recover 1 per scene, and get a full refill every time Emotion Level rises. Staggering or defeating a target hands back 1 Light, so a cost 1 page that finishes a wounded guest is effectively free. Cost 0 pages like Rules of the Backstreets exist precisely because the Light economy, not the hand size, is the real constraint.
Why it matters: The most underrated mechanic. Players who master this early have a massive advantage.
3. Stagger Resist and damage types
Every hit reduces HP and Stagger Resist on separate tracks with separate resistance tables. Drop a character's Stagger Resist to zero and they discard all dice and pages for the following turn. Resistances run Ineffective 0.25x, Endured 0.5x, Normal 1x, Weak 1.5x and Fatal 2x, listed per damage type, so a guest can be Endured against Slash on HP while being Weak to the same Slash on stagger.
Why it matters: Unlocks a new layer of gameplay depth once understood.
4. 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. Clashing gives 1 Emotion Point, rolling a die's maximum or minimum gives 1, defeating a target gives 3 positive points and losing an ally gives 3 negative ones. Each level adds 1 maximum Light and refills Light, level 4 grants an extra dice slot and level 5 improves the draw.
Why it matters: The tactical edge that separates average players from advanced ones.
5. Books and Reception invitations
Beating a guest drops their Book, which you burn at the desk for Key Pages and Combat Pages. Books double as invitations, so you pick which guest arrives next instead of being pushed down a fixed track. That is the loop: the pages you strip off one reception are the pages you need to survive the one you deliberately schedule after it.
Why it matters: The endgame optimization mechanic. Small improvements here compound into massive gains.
How These Mechanics Combine
Understanding how mechanics interact is where real optimization happens:
Clashes and speed dice + Light and page cost
At the start of each scene every character rolls speed dice, and those results set both turn order and who can be targeted. When combined with Light and page cost, light pays for combat pages. This combination is the core of every effective build.
Stagger Resist and damage types + Emotion Level
Every hit reduces HP and Stagger Resist on separate tracks with separate resistance tables. Paired with 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. This is why the tier list favors builds that leverage both.
Books and Reception invitations as a Multiplier
Beating a guest drops their Book, which you burn at the desk for Key Pages and Combat Pages. Books double as invitations, so you pick which guest arrives next instead of being pushed down a fixed track. That is the loop: the pages you strip off one reception are the pages you need to survive the one you deliberately schedule after it. This system amplifies everything else. The better your Books and Reception invitations optimization, the more your other mechanics pay off.
Combat by Build
Each build approaches combat differently:
Floor of General Works (A-Tier)
Combat approach: Balanced combat style. Key equipment: Slash dice Primary mechanic: Clashes and speed dice
Floor of General Works offers a solid combat experience. Full setup in our builds guide.
Floor of History (A-Tier)
Combat approach: Balanced combat style. Key equipment: Pierce dice Primary mechanic: Light and page cost
Floor of History offers a solid combat experience. Full setup in our builds guide.
Floor of Technological Sciences (A-Tier)
Combat approach: Balanced combat style. Key equipment: Blunt dice Primary mechanic: Stagger Resist and damage types
Floor of Technological Sciences offers a solid combat experience. Full setup in our builds guide.
Floor of Literature (A-Tier)
Combat approach: Balanced combat style. Key equipment: A Zwei Fixer's Page Primary mechanic: Emotion Level
Floor of Literature offers a solid combat experience. Full setup in our builds guide.
Floor of Art (A-Tier)
Combat approach: Balanced combat style. Key equipment: A Grade 7 Fixer, Page 1 Primary mechanic: Books and Reception invitations
Floor of Art offers a solid combat experience. Full setup in our builds guide.
Advanced Combat Techniques
Damage Optimization
- Match your equipment to your build's stat priorities
- Exploit Clashes and speed dice for maximum damage windows
- Chain Light and page cost and Stagger Resist and damage types for combo damage
- Use Emotion Level to create openings
Survivability
- Learn enemy patterns before committing to attacks
- 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.
- Position using Clashes and speed dice to control spacing
- Save defensive options for guaranteed survival, not comfort
Boss Combat
Bosses test your understanding of every mechanic. See our boss guide for fight-specific strategies.
- Phase awareness: Most bosses change behavior at health thresholds
- Patience over aggression: One extra hit per opening beats dying to greed
- Build preparation: Swap gear and equipment for specific fights when needed
Common Combat Mistakes
- Button mashing: Committed attacks have recovery frames. Mashing locks you into animations.
- Ignoring Light and page cost: This mechanic exists for a reason. Players who use it take significantly less damage.
- Wrong equipment for the situation: Check our weapons guide for situational picks.
- Not learning from deaths: Every death teaches something. If you don't know why you died, you'll die the same way again.
- Overcommitting: Trading hits works in Canard but will get you killed in Urban Nightmare.
More Library Of Ruina Guides
- Library Of Ruina Library Of Ruina Overview
- Library Of Ruina Best Builds
- 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 Boss Guide
- Library Of Ruina Maps & Locations
- Library Of Ruina Crafting Guide
- Library Of Ruina Classes & Characters
Similar Games
If you enjoy Library Of Ruina, check out these related guides:
- Slay the Spire Combat Guide: card-game game with similar mechanics
- Balatro Combat Guide: card-game game with similar mechanics
- Sultan's Game Combat Guide: card-game game with similar mechanics
