It seems like Fatal Push has invigorated multiple different color combinations in Modern that had heretofore been forced to have access to one of two premier one-mana removal spells: Lightning Bolt and Path to Exile. Sultai was the most obvious choice because it lacked either, but combining Fatal Push with one of the others is also unsurprisingly quite powerful.
Path to Exile may only cost one mana, but it's terrible to cast on turn 1, because that's when the downside of giving your opponent a free basic land is at its worst. It also pairs nicely with Fatal Push (or at least more nicely than Lightning Bolt) because it handles the creatures that Fatal Push misses, most notably the delve creatures: Gurmag Angler and Tasigur, the Golden Fang.
All this cheap removal is going to want to pair with blue, where you have access to Snapcaster Mage and Jace, Vryn's Prodigy to buy them back for more value, but the real key is what to do with the tempo advantage from all of this.
Lingering Souls and Liliana of the Veil are great at grinding over a long game, using your removal and blue card draw to gain a resource advantage, but in Modern, it pays to be aggressive, and when it comes to aggression in Esper, it all starts with Geist of Saint Traft. Six power for three mana is as good as it gets on rate, and when playing against Death's Shadow it's important to do your damage in large chunks so you can end the game quickly and not let their Death's Shadows get large enough to race.
I do worry that this deck has too many three-mana cards, especially because Snapcaster Mage is mostly a three-drop as well and a turn 2 Jace, Vryn's Prodigy is going to want to transform on turn 3 and flashback a spell immediately. This could lead to some clunky draws where you can't double spell that often, but when your removal is cheap enough and your threats are powerful you can overcome some curve issues.
If you do find yourself clumping on threes, try to aggressively loot away your Lingering Souls, effectively turning your three-drop into a two so you can get some Spirits down while flashing back a removal spell, discard spell, or cantrip. Then you can follow up with your Geist of Saint Traft and start beating face. But if you want to attack for six on turn 4, I won't hold it against you. Who could resist that?
- 2 Gurmag Angler
- 2 Snapcaster Mage
- 4 Geist of Saint Traft
- 3 Jace, Vryn's Prodigy
- 3 Tasigur, the Golden Fang