The Definite Strike is a predefined chain of regular attacks, artes, and rarely Blast Calibers that are assigned to nearly all enemies in the game. Each enemy requires a different chain of attacks performed by a specific playable character, involving only the attacks available to that one character. Successful completion of this combo chain for the first time on a given enemy will enhance all item drop rates for that enemy to be 100% during that battle, excluding enemies within the Arcana Ruins. The chance to steal items is unaffected. Subsequent activations of an enemy's Definite Strike will only double item drop rates. A successful Definite Strike will also guarantee that the enemy is inflicted with the "Stun" status ailment for two seconds.
All completed Definite Strike chains are recorded within the in-game Monster Zukan (モンスター図鑑?, "Monster Book"), on the last page of each enemy creature's entry. All of this recorded data will be carried over to subsequent playthroughs without requiring any inheritable options from the Advanced Game menu. Unique equipment awards and material components are available for various characters at the Neuestadt Coliseum if the Definite Strike records are completed for all creatures that can be found within the territorial areas of various countries and continents of the world, with further rewards upon full completion for all enemies in the game.
The ability to perform Definite Strikes is enabled after acquiring the Definite Senki (ディフィニット戦記?, "Definite Battle Record") book, which becomes available at any weapon shop after performing a combo of 30 hits or more in one battle. This book allows the player to enable or disable Definite Strikes within the Options menu. Definite Strikes cannot be activated or recorded unless this option is enabled. The option to turn off Definite Strikes exists because of the possibility that enemies may unintentionally survive attacks if a Definite Strike chain is accidentally initialized by the player. Definite Strikes can be performed only by the character in the first controller position. Any enemy that has a Definite Strike involving that character will have a "DEFINITE" label displayed over the targeting icon. Only one enemy with the same name can be subjected to a Definite Strike per battle; any other enemies with the same name will be unaffected by repeating the Definite Strike chain in the same encounter. Furthermore, Definite Strikes cannot be performed on Simple difficulty. Definite Strikes may be performed by the Narikiri Doll versions of any character.
A Definite Strike will begin only if the targeted enemy has enough HP to survive the initial attack in the required combo chain. While performing a Definite Strike, the targeted enemy will not be reduced below 1 HP, causing it to be defeated only after the required chain of attacks is completed successfully. As a result, it is possible to weave in additional attacks and artes that are not part of the required chain, enabling longer combos to be performed without defeating the enemy until the activation of the final required attack. This is especially useful for enemies with low HP, provided that the character has enough Chain Capacity to perform all necessary actions for the combo.
Any interruption to the combo chain will simply leave the enemy at its current HP level, and the Definite Strike must be attempted again from the start of the required chain. To prevent the chain counter from resetting due to spellcasting delays or limited Chain Capacity, it is possible to use time-stopping effects like the Hourglass item or Stop Flow activated by multiple party members using Philia Felice's Narikiri Doll. It is also beneficial to take advantage of Stahn Aileron's Swordian Device skill "Heavy" to increase enemy stagger duration, which affects the attacks of any other character Stahn is imitating when he equips their Narikiri Dolls. Other passive skills and re-rised Jewels that can inflict status ailments that do not reset the combo counter may also be advantageous for completing Definite Strikes, such as "Stun", "Sleep", and "Stone". Spellcasting delays can also be mitigated through the casting time reduction effect from chaining multiple different attacks and spells into a single combo before activating the intended spell, potentially reducing the casting time to zero.
The discovery of new Definite Strike chains will depend on player experimentation, if the player chooses to avoid the use of resources outside of the game. After discovering the first attack that initializes a Definite Strike, the next required attack is shown on a "Strike Chain" prompt on the top-left corner of the screen, and each succeeding action will appear after that prompted attack is completed in one combo chain. Failure to complete the required actions will cause the prompt to fade away with a "Try again..." message. Many chains can involve artes that players may not use normally, which prevents the Strike Chain pop-up from appearing until the player uses an attack that starts the required chain for a given enemy. This forces players to change their equipped arte shortcuts or controlled character frequently upon encountering new enemies to discover the correct attacks needed to begin and continue a Definite Strike. Some Definite Strikes may call for the use of an attack with a particular damage type or elemental attribute. Any attack or arte that utilizes this attribute may be used to fulfill the combo requirements, generally including regular attacks made by the designated character.
In Tales of Destiny: Director's Cut, a new coliseum battle mode was added to the Neuestadt Coliseum, the Definite Mode (ディフィニットモード Difinittomoodo?), which allows the player to select any previously encountered enemy and fight it in a one-on-one match with a chosen player character. The enemy cannot be defeated by any means unless the Definite Strike chain is performed successfully. If the ability to perform Definite Strikes had been disabled in the Options menu, this battle mode will automatically enable the option and leave it activated even after the player leaves the coliseum.
This mode allows players to attempt the Definite Strikes without the support or interference of other party members, and with no special restrictions on item use or equipment changes. The player may continue to attempt the Definite Strike until the controlled character is knocked out, and the option to escape the battle is available at any time. This also makes it possible to retry boss enemies that would otherwise be unavailable until later playthroughs, if the player had previously failed to achieve the required chain of attacks during the original encounter of the normal storyline.
The chosen player character will be the actual character and not anyone else with the Narikiri Doll of that character, which means it is possible to play as the original Leon Magnus even after he leaves the party in the "Stan Side" storyline. Accordingly, his equipment and Swordian Device can be modified during this time. Likewise, in "Leon Side", the actual characters will be chosen, but due to the timeline of events that enable Leon to access the Neuestadt Coliseum for this mode, Garr Kelvin will use the "Royal Blade" weapon during battle. As a result, Garr cannot access his own Swordian Device, and his damage output and Chain Capacity range is limited to the stats of his weapon. If any character other than Leon is used for Definite Mode, any equipped jewels will be removed automatically after the end of battle. Lilith Aileron cannot be chosen for Definite Mode on "Leon Side".
If the chosen character is holding a Narikiri Doll before starting the encounter, then the copied character will appear in battle. However, doing so will render it impossible to activate a Definite Strike since the base character will be required to perform the necessary chain of attacks. Since Narikiri Dolls cannot be unequipped during battle, it becomes impossible to win the encounter, forcing the player to escape or allow the character to be knocked out.
- Only one enemy on "Stahn Side" lacks a Definite Strike, Ilene Rembrandt. It is impossible to initiate combos on her during battle because of her defensive shield. Her accompanying machines do have a Definite Strike. Because of this, Ilene cannot be selected for Definite Mode at the Neuestadt Coliseum, but it is possible to challenge her again as part of the Rank 6 boss rush mode.
- During the "Leon Side" storyline, all of the characters that would normally be part of the party also lack a Definite Strike. This is because they all lack entries within the Monster Zukan and therefore cannot have any Definite Strike data associated with them.