It's funny you say that the reality of the comic highkey uses D&D as a foundation, I also sometimes roll dice as apart of the writing process (and to get numbers in there)
Anywho...
Lanny (Chosen one): Vengeance Paladin (5th level), Lucky Feat, to reflect inevitability and his chosen one esk prophecy. Would constantly have foresight on him :U
Mira: Eldritch Knight (5th level), with some kind of fire-themed booming blade that triggers on forced movement as well (she can never trigger forced movement herself), and a general explosion attack that deals far less damage but the effect is immediate.
Sally (The Dark Lord): Great Old One Warlock (because it's the closest match thematically), Also with some kind of foresight spell.
Koah (TDL's right-hand man): Paladin, but I won't reveal much more until later pages xD. he is not an oathbreaker, even though he DID break a previous one for the sake of literally the dark lord. Completely different oath.
Koah Spoilers
he is canonically a redemption paladin, Since the point of his character is that he sees good in everyone, even Sally who is the great evil in the world. One is a pacifist, the other is death.
His greatsword vessel has the ability to break weapons and armor, without doing a single point of damage to his enemies. And Koah has a lot of negation/counterspells to deal with spellcasters, as opposed to fizzling the spells, he weakens the spell so hard that it turns into flowers/feathers instead of something actually harmful.
Shadowy rogue character: Is a rogue (some kind of saboteur rogue archetype, about bomb planting.) has an ability that can create an explosion that forcefully moves the target, great synergy with Mira's other explosion move.
The Hemomancers: Oddly, some might be wizards, but the practice could also fit into being monks. This was realized later on in the writing process of Doomed One(s) since their practice is all about precise control over their own body (and others if you're well trained enough). Their fighting style is very acrobatic and weakspot focused which is big monk themed. The hemomancer who lacks eyes on their bird mask would be some kind of mercy monk/wizard of some sort.
yeet
https://tapas.io/series/Doomed-Ones