In case anyone hasn't noticed by now, Spell Queller is really good in Modern.
The card made an immediate impact in Standard as part of Bant Company but proved to be somewhat overrated in that format, eventually becoming a liability, especially while on the draw. Yet it fits perfectly into the current Modern format.
Lightning Bolt is down and it survives Fatal Push without revolt. It counters nearly every relevant card in the format and is never without a key target in a matchup. It sufficiently pressures opponents once on the battlefield and is an easy card to cast in any remotely reactive deck. It's also among the best cards in the resurgent Jeskai Control/Tempo deck, but that deck is boring.
This is Modern, and we can do a whole lot more than cast all the cheap removal and Snapcaster Mages until our opponents die. Ancestral Vision and As Foretold make a sweet combo for control decks, but that combo points toward playing a longer game than Spell Queller wants. We need a creature that plays well with cheap spells so it will fit with As Foretold but can end games quickly to give the deck more versatility.
Are you thinking what I'm thinking? Monastery Mentor! The card is so powerful that it's taken over Legacy and Vintage before being forcibly extricated from both formats. It only takes a couple of spells before a spot removal spell is completely irrelevant, and against control decks, the card can easily lead to Turn 4 or 5 kills. It's perfect.
The rest of the deck is pretty straightforward, with a little bit of spice to make As Foretold better. Mana Tithe is my personal favorite, and is probably an underplayed card in Modern because you're going to get a free tournament where no one plays around the card. But Azorius Charm is also nice, since the lifelink will occasionally come up when you have a battlefield full of Monk tokens.
This is what I can get behind for a Modern control deck. The As Foretold / Ancestral Vision engine can bury opponents going long, but Monastery Mentor and Spell Queller can bury them in the mid-game, so it's hard to prepare for. You can't be one-note in Modern unless you're comboing them by Turn 4, and this deck embraces that fact while retaining its strategic identity.