Tales of Vesperia: Definitive Edition
53 Achievements
1,000
150-200h
Secret Mission 13
Time your strikes between Nan and Tison's attacks to knock them down. Details for this achievement will be revealed once unlocked
15
2.37%
How to unlock the Secret Mission 13 achievement in Tales of Vesperia: Definitive Edition - Definitive Guide
Tison - Dragon Blade: Advent
The second part involves Nan. She will use Rending Slash, where she will jump in the air and then land with her blade stuck in the ground. Knock her down after she uses it.
Nan - Rending Slash
Both have to be completed. Once you see Great!!! on your screen for Nan and Tison you're good to go.
I managed to get both using a simple Azure Blast on normal difficulty without needing to spam attacks my first go around.
For the clips in my New Game+ run, BOTH bosses used their attacks within SECONDS of each other. The Nan clip begins where the Tison clip left off. Lucky me! :)
The difficult part in my opinion is actually getting them both to use these Artes, especially Nan. If you whittle her down enough, she will almost focus exclusively on healing and spells which can be really annoying. It's best to do Nan first earlier if you can, then focus on Tison. Tison uses his Arte more than Nan, so it shouldn't be too much trouble. If you get overwhelmed, turn down the difficulty to prolong the battle if you're dieing a lot.
This mission isn't so bad, so long as Nan actually decides to use her attack. Tison will use a move called Dragon Maw that will make his hand stick in the ground, while Nan uses a move called Rending Strike where she will land upside-down with her weapon stuck in the ground. You need to hit both of them at some point while they are stuck, and see the "Great!" message twice, once for each of them. I got Tison done first and killed him, but forgot Nan could heal, so she resurrected him and then refused to use anything but spells for a while. So, I'd suggest getting Nan done first instead for that reason, but it doesn't really matter.