Tales of Vesperia: Definitive Edition
53 Achievements
1,000
150-200h
Secret Mission 25
Defeat Duke using a mystic arte during your second battle against him. Details for this achievement will be revealed once unlocked
15
1.04%
How to unlock the Secret Mission 25 achievement in Tales of Vesperia: Definitive Edition - Definitive Guide
1) Press for level 3 Overlimit (requires Limit Trio from Synthesis).
2) While in Overlimit, use an arcane, altered, or burst arte. While you are performing the Arte, hold down the attack button. (This will be whatever button you have mapped for normal attacks)
3) Once the Arte finishes and you are holding down the attack button, your character should perform the Mystic Arte. (Requires Special Skill, which is gained through characters various weapons).
The easiest character to do this on is Yuri because his Mystic Arte is pure damage and you should have learned this from his Dein Nomos or Second Star weapons. Estelle, for example, has a healing part to her Mystic Arte so you may not do enough damage to kill Duke if you misjudge the damage.
Just use the Mystic Arte on whatever character you're most comfortable with judging their damage numbers on.
You will know if you got the mission done because the boss will die immediately after using your Mystic Arte.
Once Duke's health is low enough, go into Overlimit, use an arcane arte, then hold while performing that move to launch into your mystic arte right after. This easily does over 20k, so again have him under that or even lower to be safe of a kill.
For the final mission, you'll again need to have the ability to use a Mystic Arte. Either have a weapon with the "Special" skill equipped, or learn Special and add it to Yuri's move set. Now, to defeat Duke with this move you'll want him at about 20k health or lower on Normal difficulty. The less health the better, though you also don't want to run the risk of killing him with your arcane arte before even getting the mystic arte off. This will be done during his second (white) form.
Once Duke's health is low enough, go into Overlimit, use an arcane arte, then hold while performing that move to launch into your mystic arte right after. This easily does over 20k, so again have him under that or even lower to be safe of a kill.