Parent Service: In season 2 episode 8, Sadlygrove not only blurts out that he'd already seen Evangelyne naked, but helpfully specifies that it wasn't in a dream, thus excluding the mirage from episode 22. Eva's flushed reaction only makes it worse. By this point everything related to the relationship between Grovy and Eva has officially migrated from Getting Crap Past the Radar into Parent Service, as even kids need to be unusually dense to not realize that they are lovers.
Le Parkour: Evangelyne and Remington perform a quite impressive chase all over the chaotic, unstable, ever-shifting "cityscape" of Rubilaxia.
Nox healing Alibert of his premature aging in episode 13 of season 1.
Also the Brakmarian delegate in the Council of Twelve meeting in season 2. Brakmar may be a Wretched Hive, but they believe that everything has to be paid for; the delegate tips the Sadida servant, and she's visibly joyed over it.
Portal Cut: The large horizontal portal build by Nox's minions cut down everything it intersect, and then destroy all that fall into it — mostly the upper parts of trees — to make place for the giant clockwork mecha.
Portal Network: A series of portals, called the Zaaps, links different locations in the world. Since the world of Wakfu is basically a huge archipelago, it makes sense.
Possession Implies Mastery: While Nox managed to work out some of the Eliacube's functions (over a few hundred years) and use them to an astonishing extent, only an Eliatrope could truly master it.
Powers in the First Episode: Yugo discovers his Eliatrope abilities to open portals, and a few minutes later use them to help defeating a Rubilax-possessed Sadlygrove. This starts the main plot, as 10 years before Grougaloragran "programmed" one of Az's feathers to deliver a message to Yugo when this would happen.
In season 1 episode 22, at the start of the fight against Rubilax, it seems at first that Sadlygrove has the upper hand, raining blows on the Shushu. But Rubilax just laughs it off, complains that it tickles... before starting to grow and revealing that the harder he's hit, the bigger he gets.
Also happens shortly in season 2 episode 5 at the start of the fight against the Dragon-Pig.
Pure Energy: Razortime fires "Pure Stasis" — concentrated negative wakfu. According to Adama´, nothing is more dangerous.
Quirky Miniboss Squad: Nox's puppets (Marama, Frisco, Tartufo, and later Deserboss) are this to some extent.
Repetitive Name: In the first WAKFU Heroes graphic novel, Korvus Korbiau. Corvus is the genus to which ravens belong, and Korbiau is one vowel away from corbeau, which is the French word for raven. As you've probably guessed, he's the original Black Raven.
Retcon: Episodes 4, 5 and 7 were produced first, with a bit of Executive Meddling. As such, they are rather outside the overall plot of season 1, containing very little mentions of Nox or Oma Island. The only reference to an overarching menace is Eva talking about "Ogrest's Chaos" in episode 5, which was then retconned to have happened 200 years before.
The Reveal: Episode 26 of season 2 finally reveals that under an Eliatrope's hat is a pair of dragon-like wings made of wakfu protruding from his/her head, which also seems to give them the ability to fly.
Reverse Arm-Fold: Nox does this for a big part of the battle in episode 17, not even caring about Grougaloragran, who he lets his puppets take care of.
Rhymes on a Dime: Adama´ delivers a hurricane of rhymes in his introduction to Yugo, and given that French has fewer suffixes than English, the viewer gets the sinking feeling that he could keep it up forever. And then Yugo starts doing it. Luckily, they both drop it after about ten minutes.
Ribcage Ridge: Yugo stumbles onto the skeleton of a dragon in the desert during episode 21 of season 1.
Riding into the Sunset: Well, flying into the sunset for Phaeris and the heroes at the end of season 2. And for Remington and Grany too, although it's doubtful their leaking sub will get them very far.
Rip Tailoring: In season 1 episode 22, Sadlygrove rips off his tabard and leaves behind his shoes, as they sport the symbol of the Shushu Guardians Order, which he no longer deems himself worthy of. At the end of the episode, he gets them back, turning the tunic into a Badass Cape.
Prince Armand, princess Amalia, and their father the Sadida king all fit this trope. These three are also probably the most powerful Sadidas in the series, which may have to do with their special link to the Tree of Life.