This is Only Dialogue Tips for Fantasy writing, dear Skylights.

1. On-The-Nose Dialogue

2. Repeated Beats

Avoid repeating similar statements or emotions unless they are going to progress the story along. This does give you a clue and ties into one of the other six markers total to be discussed in this chapter specifically Info Dumping.

3. "As You Know" Setup- when two or more characters explain something to each other they already know.
It becomes a fake and artificial conversation, Skylights.

4. Convoluted language-sometimes a writer can get carried away with complicated phrasing and extravagant word choices. This can indeed produce again a fake feeling that yanks readers out of your fantasy world.

5. Contrived Setups- this is purely when you give one character a chance to say something just for another to reply with an actual Zinger.
This is the problem with Stella's remarks towards Riven in Season 1 episode 4 they are a very contrived setup. Stella has no reason to be saying them because she has no proof of his behavior of being rude.
Riven doesn't hate on Bloom though not just because she helped safe his life twice but also because she barely gives him dishonest remarks. She knows he can be rude but ahe also has seen his soft side too.

6. Info-Dumping can be related and occur with the same places near and have convoluted language and often too many repeated beats.
Dialogue is a tempting tool writers want to use to describe your world such as your magics, your politics, your setting, your history etc.
Number 1. Rule with Info-Dumping don't give it to all one character when you have more than one character in the scene to utilize and develop.
And don't be over-reliant on talking through info-dumping gifts to readers rather than it actually being related to what the characters would actually say to each other in the scene in the category of info-dumps.
Any time you have a class like setting Info dumping can not only progress plot, develop many different inexperienced characters, and open more about the world and also reveal hidden untold past secrets even the professor have and the best thing about a classroom setup is it doesn't have to take place inside it can be out in Nature too.

The Winx actually do gives us a very good way to an info-dump on the Magix realm and how many places are on its planet and what they actually do there in Season 2 in Palladium's class.

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Right off the bat Palladium gives us a cue to prepare for an info dump at the beginning of this episode.
"All right, I will give you each of you a chance to explain your midterm reports. Flora, you will start us off, please."

"Our report on the Magical Dimension is the one—" Palladium interrupts her as she was reading. She paused and meet his eyes, "Um, Flora, don't read it. I want you to explain it in your own words."
And for there on out because Palladium's smart all the Winx get to use paraphrasing and the info-dumping isn't thrown at the rest of the classroom nor at us. Palladium knows what a boring classroom is and what it results in and he tries his hardest to not make his class lectures of his own and from other students not sound boring but fun. This is what makes him a good teacher. When he interrupts Flora he gives her an opportunity to be less nervous and shy and to broaden other people's view point of hers by challenging her to explain her report in her own words. Paraphrasing your own words is a huge, huge challenge to pass, Skylights.

Good Dialogue Pointers
1. Good Dialogue Progresses The Plot.

2. Has meaningful subtext for the readers about the characters.

The SAID Words are text, the UNSAID & The UNSAYABLE Are two different types of Subtext. An Unsayable thing is something your character isn't or wasn't aware of about themselves yet.

Musa's dialogue in Season 4 heavily relies upon the subtext of what she can't admit saying yet.

3. Good Dialogue NEEDS To Build Personality & Uniqueness to your Characters.

4. Dialogue NEEDS To Convey Information Naturally.
Don't over do it on pauses and stutters; the time to use those are to do it when you wish to build up suspense so use them infrequently. You don't want to be too overboard realistic with dialogue that can also cut away from the fantasy aspect of the story as well.

5. Dialogue = Last Resort
I like to simplify that Dialogue in Movies is often used as a last resort. This is not a hard & fast rule in writing books though.
Dialogue shouldn't always be the first tool you reach for when it comes to conveying emotions, information and characterization.
Aisha's character build fills each of those check marks. She just use or say a lot of dialogue her actions speak so much louder than her own words.
Whereas Stella uses too many words to hide her real conflicted nature beneath her skin, Skylights.
Bloom's is equal on both the show & telling aspects of writing.
If you can make your readers sure that your character is afraid through description or symbolism or imagery or immersing us within their internal state tone that you are using to describe the world around them. That is always going to be more impactful than having a character say, "I'm Scared!"
Pixar studio staff call this the "Two + Two Rule" essentially the idea here is that you don't want to tell characters that 2+2= 4. Just give them 2+2 and have them work it out themselves that it equals 4. When you do that, you make your characters interpret the information you give them, and it produces a much deeper connection with your story. So in other words your characters should be paraphrasing the author's voice of information.

This explanation comes from Jed Herne's youtube channel, Skylights.