Eternal Sonata's Battle System is engaged by the player's character making contact with an enemy character on the main map. This switches the game's perspective to a circular battlefield where up to three allies engage up to three enemies.
A tutorial of battle basics is available when Polka first engages an enemy. A tutorial on special attacks is available when Allegretto and Beat first engage an enemy.
The player characters can gain the advantage of a surprise attack by making contact with the enemy's back on the main map. This results in the enemies' backs being turned to the players as well as the players having one full round of combat to themselves. These roles can be reversed if the enemy somehow makes contact with the player character's back to engage battle.
Light and Darkness
Different parts of the battlefield are in light and others in shadow, and these areas can sometimes change throughout the battle.
- An ally's Special Attacks will change depending on whether he/she stands in light or shadow.
- Certain creatures will morph into different ones if it moves from light to shadow and vice versa.
- Certain innate enemy qualities and certain ally status alterations can cause them to project auras of light or shadow, affecting the battlefield accordingly.
Tactical Time and Action Gauge
At the beginning of a player's turn, the Tactical Time (the time on the upper left of the screen) starts to run down (if limited), as long as no action is taken. This, as the name implies, gives time for the player to develop the proper tactic for the character to employ for that turn.
If the players takes any action, or if the Tactical Time expires, the Action Gauge starts to run down (the gauge along the left side of the screen), and the player's character is expected to move, act, and fight in this time. Player actions are limited by this gauge, and while scoring normal attacks on enemies does provide a small amount of additional time, the gauge will eventually expire, at which point the character's turn ends. Enemy actions are also limited by this gauge.
A Next indicator and arrow is shown on the battlefield, showing whose turn is next when the current character's Action Gauge expires. If the indicator is yellow, the enemy pointed by the arrow will be next to act. If the indicator is blue, the ally pointed by the arrow will be next to act, and a similar indicator will appear above that character's portrait at the top of the screen.
Varying aspects of the area traveled, certain accessories available to characters, and certain attacks inflicted by characters can inflict different effects upon a character. Status effects are indicated by visual cues overlaid upon a character as well as icons below the character's information at the top of the screen. Many of these effects are cumulative.
- Air Body—Character does not project a shadow and is not affected by character auras or shadows. Light/Dark special attacks are only affected by the battlefield. Dissipates after four turns.
- Burst—Character's attack power is doubled and defense halved. Dissipates after four turns.
- Darkness Body—Character projects a shadow around him/her/it. All special attacks will be Dark-based. Dissipates after four turns.
- Passive—Character cannot counterattack (only applicable at Party Level 4 and up).
- Poison—At the beginning of a character's turn, his/her/its HP are reduced by a certain amount.
- Regeneration—At the beginning of a character's turn, his/her/its HP are increased by a certain amount. Dissipation time varies on source.
- Shining Body—Character projects an aura of light around him/her/it. All special attacks will be Light-based. Dissipates after four turns.
- Slow—Character's battle speed halved. Dissipates after four turns.
- Stop—Character unable to move for 1-2 seconds. Reduce stop time by repeatedly attempting to move. Dissipates after four turns.
By holding the Left and Right Bumpers (or L1 and R1 for PS3) all characters will perform a fleeing animation. Fleeing battle is useful when you are in a tough situation where you risk a Game Over, however in some cases can be dangerous. Fleeing can be done at any time during your character's turn, but will only be successful if it is performed just when the Action Gauge begins to deplete itself. Be aware that if you did not begin to flee early enough you will not flee, your turn will end, and it will be given to the next person. Fleeing will always be successful assuming that the condition is met. It is useful to hold the buttons slightly before it is the character's turn so that when it is their turn, they immediately begin to flee. After a successfully fleeing a battle, the character on the field will begin to blink and is unable to enter battle. Enemies will ignore the player and not chase you.
Hint: During the invulnerability period after fleeing, you are free to heal in the menu. Also, as the enemy ignores the player while invulnerable, you can run behind the enemy and initiate a Surprise Attack when the invulnerability period ends. If you have a very fast character in your battle party, that character might take the first turn before any enemies can in a regular battle. If that is true, you may immediately flee into the invulnerable period and do a Surprise Attack, giving your team and advantage.
Varying advanced battle techniques can be unlocked depending on the current Party Level. A tutorial on the tradeoffs of Party Level 2, including Echoes, is available when Allegretto and Beat first engage an enemy at Party Level 2.
- Unlocked at Party Level 2.
Echoes are a form of power-building. As allies score hits on enemies using normal attacks, they build Echoes. The lower right corner of the screen will indicate when you hit 4, 8, 12, 16, 24, and finally 32 Echoes. When an ally invokes a Special Attack, they consume these Echoes to increase the power of their Special Attack. Although Echoes are consumed when the Special Attack is invoked, the attack itself becomes the beginning of a new series of Echoes (this is most notable when the attack is multi-hit).
Invoking a Special Attack with at least 24 Echoes will trigger an extended animation for the attack. At least 24 Echoes are also needed to create a Harmony Chain.
- At level 6, Echoes in possession will be carried over through battles. Fleeing will not cause you to lose echoes.
Secondary Special Attack
- Unlocked at Party Level 3.
When a different attack is assigned to a character's secondary special attack, holding the Special Attack button will cause the special attacks to cycle between primary and secondary. Releasing the button will invoke the attack currently displayed.
- Unlocked at Party Level 4.
When an enemy first attacks, there is a chance that the timing prompt to defend the enemy's attack shows a Counterattack icon instead. When this is shown, you can press the Attack button instead of the Guard button to perform a Counterattack. Pressing Guard during a Counterattack prompt will cause you to simply guard. Pressing Attack when there is only a Guard prompt will cause you to fail the Guard. Pressing Attack and Guard at the same time will result in a failed Guard. Performing a successful Counterattack will cause any damage done by the enemy's attack to be negated, end the enemy's turn, and knock them down. The character who performed the counterattack is given 1.5 seconds of Action Gauge to freely move and attack. Counterattacks do not count as turns and do not cause Regen or Poison to take effect.
- At level 4, you can only counterattack with your normal attack.
- At level 5, you may also add Special Attacks into your counterattack.
- Unlocked at Party Level 4.
With at least 24 Echoes and different moves assigned to a character's primary and secondary special attacks, when a character performs a Special Attack, a timing prompt will appear towards the end of the move. Press Special Attack again in time and the character will perform his/her other Special Attack in a powerful Harmony Chain.
- At level 4, only the initiating character's two Special Attacks can be chained.
- At level 5, the Special Attack of another ally within range can be chained to make a third link.
- At level 6, both Special Attacks of all three allies can be invoked to create a complete six-link Harmony Chain, provided all three characters are in range and have unique primary and secondary Special Attacks. Echoes obtained during subsequent Special Attacks are no longer lost.
Hint: At level 6, having a party with a set of special attacks that induce many hits on the opponent is advantageous. Performing a full Harmony Chain in this manner may very well leave you at 16 or more Echoes, where the next character may build enough Echoes to start another Harmony Chain. Another useful thing about Harmony Chains is that when you cycle through most of your Special Attacks which may including Healing. Prioritizing attacking to build Echoes and performing a Harmony Chain to heal over immediately healing is often more advantageous.
- Activated at Party Level 6.
At Party Level 6, the Attack, Special Attack, and Guard buttons will randomly reassign themselves in the course of the battle. This most significantly occurs when performing a Harmony Chain. Pay very close attention to which button is currently assigned when attempting to perform a particular action.