@Zennistrad  
@Metal Squirrel Chaos  
There’s also the option of hand destruction/manipulation (Thoughtseize) and other forms of library manipulation (Transmute). In terms of dreams/the mind, unblockable could also be good for UB flavor, mirroring the idea of sneaking into someone’s mind.  
Though, if i were to choose a deck archetype that mirrors this best while being decent, I’d go for Esper control, with mill being an alternate wincon (Nephalia Drownyard, Duskmantle Guildmage, and now Phenax) and more focus on hand destruction. You would, after all, be “controlling” the spells your opponent plays

@Metal Squirrel Chaos
 
U/B Mill tends to be heavily associated with mind and dream manipulation flavorwise, which is Luna’s forte if Sleepless in Ponyville is to be believed.

Honestly I see Luna going with mono-black control. Mill just doesn’t seem her thing.

 
You know Lyra has at least one.

@Background Pony  
@FanOfMostEverything  
 
maybe? don’t know many combos with it myself, but it seems to be MEANT for chaos
 
also, Twilight could alternatively play WUx control, probably RWU

@The Hittite  
And two Wandering Eyes.

Derpy: 59 Ornithopters and a Magikarp

@FanOfMostEverything
 
Can’t really think of anything that fits that, to be honest.

I would go with Rakdos

It certainly works in terms of “which play style best describes that pony’s personality?” That said, I’d like to see at least one unexpected disconnect.
 
Also, Pinkie totally has a deck that can reliably assemble a ridiculous fifteen-card combo that doesn’t even win the game; it’s just fun.

I see what you did there with Trixie.

yup i play just like applejack

“Neo Affinity”, for those not in the know, is different from typical affinity decks because of its greater focus on control than on hyper-aggressive combos.