Sylph: Sylph’s are similar to witches but they manipulate their aspect in a more abstract way, with a focus on healing. They can manipulate their aspect to heal it, making it thrive in their session. A common way to do this is to manifest their aspect into others. They also manifest it into the world. Their aspect is something that’s fragile or flawed in their session, and they always take it as their duty to both nurture it and fix it personally.

Doom: Fate (specifically an unfortunate fate), futility, misfortune in general, sacrifice, and death. Time has an association with death, but doom directly deals with it. It heavily involves ghosts and the afterlife. This aspect seems to be connected with rules and restrictions. It's usually tied to the specific event(s) in their sburb session that will doom everyone.

This one has a long preamble, and I apologize. Skip the paragraph below if you just wanna read the analysis straight.

So, the first sylph request I completed was Sylph of Rage. In that one I interpreted it as being an inherently antagonistic classpect to have because I view Sylph's healing their aspect to mean they don't see any single part about their aspect as something wrong with it. They don't try and improve or change it, they just manifest it and nurture it as a whole to the best of their ability. Someone else had the idea that a Sylph of Rage could be beneficial because anger isn't an inherently negative thing and can be used to help others, which is true, but I view rage as encompassing destruction and chaos in general, so it didn't change my view that classpect. I don't think that's an invalid take though, I understood where they were coming from. Sylphs, rage, and doom as well are all concepts that aren't very directly explained in the comic. I'm prefacing this analysis with this because 1) I forgot to respond to that reply before (sorry), and 2) my own interpretation of Sylph of Doom is not going to be someone that heals their session of doom. They will be healing the aspect themselves. However that last reply has led me to broaden my thought process, which ended up leading me to believe there are three different ways this classpect would work narratively, so it'll probably be one of the longest analysis's I've written so far. Whoops!

So! Doom is an unfortunate fate, misfortune in general, the restrictions their session faces, and death itself. It has a lot to do with specific major events within their game session that will restrict and negatively impact them and their teammates. A Sylph's aspect is something that's fragile, weak, or threatened within their session, and they will take it on as their personal duty to manifest it and make it stronger, and have the ability to bring their aspect out within others. They're known as a healing class because their goal is to "heal" their aspect; they can heal others through their aspect, which also serves to accomplish that goal. This is why I wrote that preamble as well as mentioned that these things interact a bit strangely, in my own opinion.

I think the best case scenario for a Sylph of Doom would be to function similarly to a time player, taking on the duties to do what needs to be done in order to prevent a doomed timeline, or keep the wrong timeline from not becoming doomed, they focus on the death and misfortune that's necessary for success rather than death and misfortune that would lead to a doomed timeline.

Because sometimes bad things have to happen in order to prevent a broken timeloop. The simplest example of this concept being that Vriska made sure Bec was prototyped because she knew their timeline would be doomed if he wasn't. A benevolent Sylph of Doom would only be able to exist in a session where a lot of bad things need to happen in order to keep their timeline stable (which ties into Sylph's aspect being weak, since they would need to make sure these things happen). This would work well if they had a Page of Time on their team or another time player who has difficulty with keeping the timeloops stable, or they could simply work together with them. They could alternatively be at conflict with one another, with the time player preventing bad things from happening thinking it's what's necessary, even though those things need to happen. It'd also work well if it was neccessary for some players to die for one reason or another.

Basically, this type of Sylph of Doom takes on the duty of nurturing doom for the benefit of their session and timeline.

Now, the more straightforward Sylph of Doom would be someone who simply wants doom to come about in a session where everything is going "too good" in order to cause a doomed timeline rather than preventing one. They would be perfect to be the main or a secondary antagonist. Maybe they're working under a higher power that wants to destroy everything, maybe they grew to hate their teammates, or they want to bring about despair just for the sake of it. All that matters is there's a lack of death and misfortune in the game and they plan to manifest it and restrict their teammates.

This Sylph of Doom takes on the duty of nurturing doom for the sake of doom. Death for the sake of death.

A combination of these two ideas would be a Sylph of Doom who manifests doom to cause a doomed timeline, but isn't a villain. If something bad would happen if their team won their session, they would do anything in their power to bring about doom to their timeline. This could be the case if the other players would be tyrannical towards the new universe they created.

This Sylph of Doom takes on the duty of nurturing doom for the greater good. Manifesting misfortune and death to those who just deserve it.

With all that said, what would their actual powers look like?

Sylph's manipulate their aspects in an abstract way, and that works well with doom, which is an inherently abstract aspect. I feel like Sylph's would be able to essentially curse others. The least to most powerful curses would be bad luck, an impending sense of doom and/or futility, a very restrictive disability, sickness, and death. They would likely have to lay their hands upon them to do so, similar to how Aranea had to physically touch Jake and Terezi to manifest light within them.