Stage Battle Mechanics
HP is how much damage a card can take before it loses the battle. A unit's HP is the sum of its cards' HPs. Individual cards cannot be defeated in battle; the player loses a stage battle when their entire unit's HP is reduced to 0.
ATK is how much damage a card does to the enemy unit. A sub-unit's ATK is the sum of its cards' ATKs. Without any modifiers, a sub-unit does exactly as much damage as it has ATK.
CP is the amount of CP required to use this card in a battle. To prevent confusion with the player's Charisma Points, this will be referred to as "cost" from now on. A unit's cost is the sum of its cards' costs. Whenever a stage battle is performed, the player must use CP equal to the cost of the unit used in that battle. Additionally, the cost of a unit may not exceed the player's max CP.
An important bonus to a card's stats is the max friendship bonus. Cards with maxed-out friendship receive 6% additional HP and ATK, which is reflected in the card detail. For example, a Level 80 GS 「二川ミミ フラワーライブ」 (Futagawa Mimi Flower Live Show) has 7500 HP, according to the card list. So, when viewing that card, its HP would show up at 7500, and 7500 would be added to the HP of a unit when Mimi is added to that unit. However, if its friendship was maxed, then it would receive a 6% bonus to its HP, changing it to 7950. This would be reflected when viewing the card's details, and in the HP of the unit Mimi is added to, and so forth. This bonus is unique because it is the only bonus that affects the display ATK and HP of a card. Every other bonus does not take effect until the card is in a stage battle.
A minor consideration is a card's type. A card whose type matches the player's specialization gains a 2% bonus to HP in battle. It is also suspected that these cards receive a bonus to ATK in battles against units of the type that the player's specialization is strong against. Some skills also target specific types.
When leveling up a card, its HP and ATK increase according to one of three formulas. Each card uses different formulas and the formula can be different for HP and ATK. It is not known what the three formulas are, but it is suspected that one increases the stat more at lower levels, one increases the stat evenly across all levels, and one increases the stat more at higher levels.
Cards appear to be valued with every 1 ATK equal to 3 HP at max level. That is, we can calculate a card's "value" as
value = 3*ATK + HP, where ATK and HP are taken from its max level, regardless of a card's skills or other stats. That is, the game considers a card with 3000 HP and 3000 ATK at max level to be equal in worth to a card with 6000 HP and 2000 ATK at max level. Value is an important abstraction because the CP of a card (that has not been type changed) is based on the value and rarity of that card. Within each rarity, cards with higher CP necessarily have a better value as well. Therefore, cards with higher cost basically have better max level stats.
Each unit may only contain one copy of the same card. However, the regular and special lesson forms of a card are not considered the same card. Type changed forms of a card are also suspected to not be considered the same card, but this is not confirmed.
Unit combos are granted when cards in a unit share certain characteristics. A list of combos can be found in the Skills and Combo Appendix. Little is known about the specifics of combos' mechanics, but they appear to grant a very small bonus to either ATK or HP to the cards contributing that combo. Most combos have been observed to grant less than a 1% bonus. Even the strongest bonuses, such as 「バルドルスターズ」 (Variety Idol Stars), which requires that every card in the unit be a Variety Idol card, are suspected to grant less than a 5% bonus, despite being very restrictive.
Battles are resolved following these steps. Note that the names of the steps are not canonical.
- Preparation Phase
- Battle Phase (repeats)
- Team 1's Turn
- Skill Activation Step
- Attack Step
- Reaction Step
- Team 2's Turn
- Skill Activation Step
- Attack Step
- Reaction Step
- Sub-unit Switch Step
- Team 1's Turn
The Battle Phase repeats up to a maximum of 50 turns, and the battle ends when either one unit has 0 HP at the end of a Step or when the 50 turn limit is reached.
During the Preparation Phase, both teams gain bonuses from unit combos, which are permanent. The team to attack first (Team 1) in the Battle Phase is also decided, but it is unknown how it is decided. Each team's first non-empty sub-unit is also made active.
During the Skill Activation Step, the turn team's active sub-unit may have one of its cards use its member skill, and additionally have its leader use its leader skill. If multiple member skills can activate this step, then one of them is chosen to activate. If both a member skill and the leader skill can activate, then one of them is chosen to activate first. In both these cases, it is unknown how the skill is chosen. Please see the skills section for more details.
During the Attack Step, the turn team's active sub-unit attacks. Each of its cards calculates its effective ATK based on bonuses and penalties gained from various sources, and the ATKs are summed together to get the amount of damage dealt to the opposing team.
During the Reaction Step, reaction skills activate in response to the damage that was taken. These skills are DMG Absorb, DMG Reflect, and HP Reduce. The opposing team must survive the attack in order to activate DMG Reflect, but it is unknown if they must survive in order to activate DMG Absorb.
During the Sub-unit Switch Step, both teams' active sub-unit becomes the next non-empty sub-unit in their unit. This can be the same sub-unit if they only have one non-empty sub-unit.
ATK Up (self) increases only this card's ATK for its next attack.
ATK Up (sub-unit) increases this sub-unit's ATK for its next attack.
ATK Up (type) increases the ATK of every card of that type in your unit for its next attack.
ATK Down (sub-unit) is suspected to either decrease the ATK of the next attacking opposing sub-unit, or decrease the ATK of the current opposing sub-unit.
ATK Down (type) is suspected to decrease the ATK of every card of that type in the opposing unit for its next attack.
DMG Absorb is a reaction skill that activates in the Reaction Step of the opposing team's turn. It increases the HP of the team by a percentage of the damage dealt in the last Attack Step.
DMG Reflect is a reaction skill that activates in the Reaction Step of the opposing team's turn. It deals damage to the opposing team by a percentage of the damage dealt in the last Attack Step.
Healer increases the team's HP. It is unknown how the amount of HP gained is calculated.
HP Reduce is a reaction skill that activates in the Reaction Step of this team's turn. It decreases the opposing team's HP. It is unknown how the amount of HP decreased is calculated.
Some skills have a condition that must be met for the skill to activate. Usually, it requires that the team's HP be under a certain percent. Other conditions, such as having at least some number of cards of some type in the team, also exist.
Every member skill, with specific exceptions, can only activate one time per battle. Every leader skill can activate an infinite amount of times.
All skills have a hidden numerical parameter that determines how effective it is. Usually, it represents a percent value. For member skills, the only way to find this parameter is either via observation and calculation, or looking it up in the game's data. Leader skills are more predictable since many of them share the same name, and skills of the same name have the same effect. Additionally, leader skills are often prefixed with "S" or postfixed with "+" which represent a stronger version of that skill. For example, 「Ｓチアアップ＋」 (S Cheer Up+) is a much more powerful version of 「チアアップ」 (Cheer Up).