The Comprehensive Ruina Battle System Guide

This is going to be hell to make.
But, if you don't want to spend 100 hours learning the ins and outs of the combat system like I did, this is the place to be.

Clashing

Clashing is the basis of much of the rest of the combat system in Library of Ruina, so it will be covered here first.

At the beginning of a scene, all guests will target librarians. If you attack them back on the same speed die, this will result in a clash. Each side will roll their dice in order, and whoever rolls higher gets to have their die go through. Pretty simple, right? Not quite. More advanced clashing mechanics are gone into later in the guide, but for now I'll cover the basic mechanics of the clashing system.

-If a defensive die is played but not clashed against, it will be stored. A one-sided attack directed at that librarian/guest will clash against the stored defensive die.

-Some cards/dice have various passive effects when played. Some of these will only activate in clashes, such as 'On Clash Win/Lose' or 'Start of Clash', et cetera. Make sure you keep an eye on these things if you want the effects to activate.

-If a combat page does not engage in a clash, it's a one-sided attack. This mostly affects abnormality pages and some combat pages, although it can influence combat strategy as well.

Speed Dice and Attack Redirection

Ever wondered what those numbers on your dice were for? That is your speed. If your speed is higher than your target's, and they weren't initially targeting you, their combat page will be redirected to clash against yours. This doesn't take effect if your speed is equal to or lower than your target's. Guests can't redirect your attacks, though some guest's attacks can't be redirected under certain circumstances.

Dice Types

Offensive Dice

Offensive dice are sorted into three types- pierce, slash and blunt. The cards show the types of dice when you are selecting them for a deck.
Remember that your opponents will have different endurances to different types of offensive dice- you can check their resistances by clicking on them in the battle prep menu or by hovering over/clicking on them while in battle.
Some passives will increase the power, damage or stagger damage of certain dice types.
Resistances in relation to damage work as so:
Fatal - 2.0x
Weak - 1.5x
Normal - 1.0x
Endured - 0.5x
Ineffective - 0.25x
Immune - 0.0x

Defensive Dice

There are only two types of defensive dice- block and dodge. Most importantly, they can reduce or entirely negate incoming damage. But, as a secondary function, they can effect the Stagger Resist (SR) of you and your opponents.

Starting with block dice.
On a clash win with a block die:
-Against an offensive die, it will entirely negate the incoming damage and deal stagger damage to the loser equal to the difference between the two dice rolls. (e.g. if you roll 10 block against 5 attack of any type, you take no damage and your opponent takes 5 stagger damage.)
On a clash loss with a block die:
-If the clash was against an offensive die, the incoming damage will be reduced by the dice value- the remaining damage will then be multiplied by the defender's resistances before being applied. (For example: if you roll a block of 6 against an attack of 8 that you are weak to, you will take 3 damage.)
-If the clash was against another block die, the loser will take stagger damage equal to the winner's dice value.
-If the clash was against a dodge die, the winner will recover stagger resist equal to their own dice value.

Now, on to dodge dice. They work very differently.
On a clash win with a dodge die:
-Against an offensive die, the damage will be entirely negated, and the dodger recovers SR equal to their dice value. The dodge die will also then recycle against any following attacks until it either loses a clash or clashes against a defensive die.
-Against a block die, the dodger recovers SR equal to their dice value, and the dodge die does not recycle.
-Against another dodge die, no effect happens on either side. Neither die is recycled.
On a clash loss with a dodge die:
-Against an offensive die, the loser will take the full brunt of the damage (multiplied by their resistances).
-Against a block die, the loser will take stagger damage equal to the difference between the two dice rolls.

Counter Dice

Counter dice (marked as gold dice in-game) work the same as listed above, except a counter die will be recycled upon clash win regardless of its dice type, against all dice on a single combat page.

Status Effects

I will not be listing every specific status effect and counter here. These are the ones that can be attained and inflicted more commonly.

Buffs

All buffs exhaust after one scene (excluding Persistence), unless applied each turn by passive effects.

Strength/Strengthened: Increase power of all offensive dice by x amount.

Endurance: Increase power of all defensive dice by x amount.

Haste: Increases speed by x amount.

Protection: Decreases incoming physical damage by x amount.

Stagger Protection: See above, but with stagger damage.

Persistence: For x scenes, if taking lethal damage, revive with 20(?) HP at an 80% chance. The chance of this effect triggering reduces by 20% each time it takes effect. (I believe this resets upon obtaining a new stack.)

Status Ailments

All status ailments exhaust after one scene, excluding Burn.

Burn: At the start of the Scene (turn), take x damage and halve the stack of Burn (rounded down).

Bleed: Take x damage upon rolling an offensive die and remove a third of the stack (rounded up).

Fragile: Take x additional physical damage from all attacks; stagger damage remains the same.

Immobilized: Character cannot act for the scene- their resistances remain the same, they are not staggered.

Paralysis: For the duration of the Scene, whenever the character plays any Combat page, up to x random dice on it have their maximum roll value reduced by 3.

Erosion: This character takes x amount of bonus physical and stagger damage upon taking a hit. At the end of the Scene, take x damage and lose 1 stack of Erosion.

Fairy: Take x damage every time the character rolls a die. At the end of the Scene, take x damage and halve the Fairy stack. It's like bleed, combined with burn, and better.

Neutral Effects

Smoke: Take OR deal (x*10)% more damage per hit based on passives.

Nullify Power: Dice played by this character are not effected by power gain or loss this scene. (Doesnt effect Haste/Bind as far as I know.)

Charge: Affects certain Combat pages. Up to 10 (20 with a particular passive) stacks of Charge can be held at one time. If up to 20 can be held, the symbol will change from blue to orange.

Emotion Level

Emotion level (EML), on any given librarian, can go up to a maximum of five. If I remember correctly, you start with a floor emotion level maximum of 3, which can also go up to five.
The floor/team EML is gauged by the averaged emotion levels of all living librarians in battle. For example, if you have three librarians in battle that are all at EML 4, the team EML will be 4.
Alternatively, if you have four librarians in battle, two at EML 1, one at EML 0 and one at EML 2, the team EML will be 2.

Team EML is the important one (in the author's personal opinion), as it gauges when new abnormality pages can be selected. Whether your options will consist of Awakening or Breakdown abnormality pages (not covered in this guide) will be reliant on the type of emotion coins you netted while raising the emotion level: positive or negative.

Positive emotion coins can be gained by:
-Defeating an enemy
-Winning a clash
-Combat page passives
-Attacking a staggered enemy(?)

Negative emotion coins can be gained by:
-An ally being defeated
-Losing a clash
-Combat page passives

When the individual (not team) emotion level rises, the librarian will restore their light to full and draw a page. Each emotion level also gives a bonus to the librarian that lasts the rest of the reception. They are as follows:
EML 1-3: Max Light Capacity +1 for each
EML 4: +1 Max Light Capacity, +1 speed die
EML 5: +1 Max Light Capacity. After playing two or more combat pages in a scene, draw an additional combat page next scene.

Passives and Attribution

I will not be covering every single passive effect, considering how many of them there are throughout the game. This will be more broad-strokes.

Passive effects are first introduced after the first main story battle. They may not seem like much yet, but they can make or break a battle.
There's a lot of different functions a passive can have, but most of them either increase damage, power, or inflict statuses on either the user, their allies or their opponents.

The passive attribution system is first unlocked in Urban Plague, with 6 available attribution slots. As the tiers progress, you will gain 2 each time, up to a maximum of 12. This can be accessed by double-clicking on the passive attribution box in either the main library menu or in the pre-battle menu.

Passives will have different costs to attribute to key pages. More powerful passives tend to have higher attribution costs and vice versa, although this isn't always the case.

Attributing one page's passives to another key page will make the attributed page unavailable for use by another librarian. You can only attribute a page to one other key page- you can't split passives across key pages unless you have multiple copies of the attributed page.

Melee, Ranged and Mass Attacks

The type of attack you are using will affect when it goes into play in a scene, regardless of speed.
Mass attack pages ALWAYS go first, although it's important to note that mass attacks played by your allies will go before mass attacks played by your opponents.
Ranged pages go next, from highest to lowest speed.
Then, melee pages go last, from their highest to lowest speed.
So remember that a ranged attack will never outspeed a mass attack, and a melee attack will never outspeed a ranged or mass attack.

There are also differences in how they clash.
Ranged pages clash with other ranged pages in the same way melee pages clash with one another (which you should have seen if you've played through any part of the main story).
Defensive dice are always played the same way regardless of whether they are ranged or melee.

Ranged pages clashing with melee pages, however, are different.
If a melee offensive die wins a clash against a ranged offensive die, the melee die will be recycled and sent to the back of the line, so to speak. This will repeat with every other die, and then once all ranged dice have either gone through or been deflected, the remaining recycled dice will be used to hit the target.

Now on to the big guns: Mass Attack pages. These attacks target all characters, and there are two types.
Summation attacks add up the rolls of every die on the page you played. If the combined rolls of all dice on the played page exceed the roll of the mass attack, it will be negated for that character. If it does not exceed the mass attack roll, the defender will be hit with the full force of the attack regardless of any defensive dice, and they will not play that page in that scene. Summation mass attacks (usually) only have one die on their page.
Individual attacks do not sum up your dice rolls. These attacks count each die separately- if any lose their clash, that die is destroyed and the librarian will not use it that scene. Individual mass attacks (usually) have more than one die, but normally no more than three.

Pages defending against mass attacks can target anything and still take effect!!! As long as you're playing the combat page on the librarian's speed die targeted by the mass attack, it will still work to negate the mass attack as long as you win the 'clash'. (It will not, however, count as a clash, so any clash-related effects will not trigger unless the combat page used also clashes against a different page.)

Conclusion

This guide will by no means make you an instant master at the game, but I hope it does help. A lot of these are things I learned from experience rather than the tutorial, so I hope this will provide either a point of reference for experienced players or give newer players a better grasp of this game's combat system.
Go out there and obtain the one true book! I hope I could be of help!

(And if I missed anything, please feel free to comment and let me know! I want this guide to be as generally helpful as possible ^^)

[cheapmoon v2]

Thank you for the guide! Never knew that hitting staggered enemies raised emotion. There are some little things i'd like mentioned:

- With ranged attacks, losing against a block die will NOT result in taking stagger damage backj
- For passive attribution, there's also a limit of 4 pages and [however many] actual passive abilities that can be fit into a single key page
- Could be nice to add that kills/deaths add 3 emotion coins unlike other means (this is just some perfectionist crap though). Also, wouldn't EML in the second example you give be 1? (1+1+0+2)/4 = 1
- This has to be checked ingame, but what happens if a page ties against a mass-summation attack? I do believe it would mitigate the damage, but whether the page will still be used is unknown to me
- Does bleed really round up? This is, once again, coming from memory, but i'm relatively sure it rounds down. Hence, if a character has 1 or 2 bleed, they won't lose any of it until the next scene

[Paintbrush Poltergeist]

Thank you! I'm rather stuck on SoTC, and I think your guide is going to be pretty helpful for me. I'll give you both an award for it!

[Dublinthedog]

Did they make the combat as confusing and convoluted as possible for a reason? Yeah this looks like a refund.

[Ekimmak]

There's a few more ways to generate Positive and Negative emotion coins, but how that works is a bit bit tricky to explain without showing.

If I play a 1 die page versus a four offensive die page, then every hit past the first die is going to generate a red coin for me, and a green coin for them.
I think that this also kicks in for "inherent" die while staggered. So, if Yujin is staggered, and gets hit by a one sided attack with four die, 4 emotion coins are generated even though it's one-sided.

You also get an emotion coin if the maximum or minimum value of a die is rolled. This makes Opportunity Spotted extremely good for coin generation, as it has three offensive die that roll 1-2.

An "On Use" effect does not trigger versus a mass attack. So something that says "On Use: Gain X Power based on Y" does not roll as strong as the numbers say they should. However, "Combat Start" WILL apply its effects.