The Combat System in Monster Musume: Everyday Life with Monster Girls Online is based on the idea of "social conflicts", where one group of Monster Girls confront another group of Monster Girls and they begin verbally antagonizing each other.
In such "catfights", "Attacks" are represented through personal boasts and cruel putdowns while "Health" is the girl's emotional stamina to endure such assaults.
Combat lasts for 3 Rounds.
During each round each girl takes a turn in attacking a girl on the opposing team.
The order in which each girl attacks is decided based on Agility stats. The girl with the highest Agility stat goes first, the girl with the second highest Agility stat goes second, the third highest goes third, the fourth highest goes fourth, etc, etc, etc.
An attacking girl may choose to use either a Normal Attack (the strength of which is decided based on the attacker's Attack stat and the defender's Defence stat) or a Skill that will enhance their Normal Attack in some way.
The defending girl may choose to either endure the attack or use a Skill that will aid their defence in some way.
During the attack/defence phases, the player can aid their Monster Girl (be they the attacker or the defender) by clicking the Master Actions button to temporarily enhance their attack or defence.
Combat ends when all girls on one team are "KO'd" or when all 3 Rounds are completed. If all 3 Rounds have been completed and both teams still have active combatants, whichever team is dominant as determined by the Combat Tracker is considered the winner.
Aside from the Master Actions button, combat is completely automated by the computer. Players can not choose which girl to attack or whether to use a skill. However, the likelihood of a skill being used can be influenced through increasing that Skill's exp level.
The player can help influence the fight by using their Master Actions button.
- Clicking when one of the girls is attacking makes the player shout "Do your best!" and causes the girl to deal double damage.
- Clicking when one of the girls is being attacked makes the player shout "Don't lose!" and halves incoming damage.
The button can only be used three times per battle.
See Also: Skills List
Each playable Monster Girl has a selection out of three skill types (1 Attack Skill, 1 Defence Skill, 1 Support Skill). While some girls have one skill, some others may have two, or even rarely all three.
There are three types of skills which are used during Combat,
- Skill 1: These skills activate while attacking during combat.
- Skill 2: These skills activate while defending during combat.
- Skill 3: These skills temporarily enhance/decrease the stats of party/opponent member/s during combat or taunt them into attacking the user.
While Combat is automatically run by the computer, players can affect the likelihood of a skill being activated during Combat by raising the skill's exp level via the Fusion System (Skills can be raised to lvl 10).
While not as critical in determining the outcome of a battle as Stats, the game also uses a rock-paper-scissors style type system. The five types are: Cute (), Passionate (), Cool (), Pure () and Devil (). Their strengths and weaknesses are as follows:
- Cute is strong against Passionate, weak against Cool.
- Passionate is strong against Cool, weak against Cute.
- Cool is strong against Cute, weak against Passionate.
- Pure and Devil are both strong and weak against each other.
The Combat Tracker is a tracking bar located along the circumference of the half-circle announcement banner at the top-center of the screen.
The bar shows which team is currently dominant during combat (Pink bar is the Player team, Blue bar is the adversary team). As a team gains domination (through various factors such as cumulative Exp Level, number of team members KO'd, cumulative health, etc) the team's representative colour (Blue or Pink) will gradually overrun the other colour and fill the bar.
In the event that all three combat rounds are completed and both teams still have active members, the winning team will be chosen based on which is dominant in the Tracking Bar.
- The representative image of each combatant will move slightly out of alignment from the other combatants to show the attacker and defender for each attack phase.
- A small light will circle around the Master Actions button twice as a lead up before each attack/defending action. Players are able to press the Master Actions button during this brief lead up period unless their three Master Actions have been used up.
- The concept of combat for the game may be based off of instances from the manga and anime where the main characters become involved in such incidents; such as in Chapter 2/Episode 1 where Miia must endure insults from The Racist Couple or Chapter 16/Episode 8 when Centorea had to similarly endure attacks from the couple before Rachnera arrived to return "attacks".