Nox was never particularly stable, but after Grougaloragran blows himself up in order to prevent Nox from draining his wakfu, (temporarily) thwarting his plans to travel back in time to save his family in episode 17, he really loses it.
He has an even bigger one when the Eliacube drains all the wakfu he has collected over the last 200 years just to travel back 20 minutes during the season 1 finale.
Qilby, too, during the season 2 finale, gets more and more unhinged following Yugo's Kirk Summation.
Villain Teleportation: Nox, and to a lesser extent Vampyro. Subverted, since Yugo also uses a form of teleportation (however, it's of a different nature than Nox's).
Voices Are Mental: Anyone possessed speaks with the Shushu's voice. That's how Eva can tell something is wrong with Grovy's body in season 2 episode 2 as soon as he talks, recognizing Rubilax's voice. Interestingly, this is true even if the host remains in control of their possessed body. This leads to a couple of instances of Talking to Himself, where Sadlygrove and Rubilax converse while in their combined monstrous form, both using Rubilax's voice.
About all of the first half of season 1, from leaving Emelka to reaching Oma Island. Largely Justified since most of the Side Quests result from Grufon (the Magic Map) leading them astray out of spite.
Then a good part of season 2, too, before reaching the Crimson Claws Island.
Rushu, the king of the Shushus, pitches a fit whenever he sees a bow-meow. They're just too cute and fluffy.
We Would Have Told You, But...: Ruel, Salygrove, and Rubilax's reason for not telling Yugo that they managed to sneak Cleophelia with them, as he was too pure to lie and would have told Amalia and Eva.
Vampyro does this to Sadlygrove with a mere touch in episode 6.
Posho at the beginning of episode 12... from the Eniripsa's vigorous "healing".
Adama´ gets his turn when struck by the giant gerbil's lightning in season 2 episode 1.
Sadlygrove's Rubilax-possessed form, while shocked by the Mini-Mecha in season 2 episode 23.
You Are What You Hate: Nox' whole plan and goal in life is to defy and "beat" the god Xelor. To achieve this he technically becomes one himself. Although Nox doesn't quite "hate" Xelor; he was just willing to go to any lengths (such as reversing time, something Xelor is unable to do) to save his family.
You Can't Make an Omelette...: Qilby quips "You can't make an omelette without breaking Dofus." while showing off the Zinit to Adama´. Foreshadowing of bad things to come.
During his fight against Nox in episode 17, Grougaloragran repeatedly calls him a madman, but Nox pays this no heed. Later, both Yugo and Adama´ give him a "You're insane!" speech at the end of the final fight in episode 26. However, since it is after Nox's whole plan is crumbling around him — with, literally, his giant clock mecha — this time the Xelor may actually be listening.
Also Yugo to Qilby.
Your Eyes Can Deceive You: Yugo has his eyes temporarily shut in episode 21 while training his wakfu-sensing abilities with Adama´.
Zerg Rush: The aptly-named "Rush" in Rushu's world consist of being attacked by 666 minor Shushus.