War of the Spark has not disappointed. As Magic's first-ever "event set" placed in the regular set release schedule, it produced a ton of hype and splashy new card designs. And now we're getting to see those do work in Modern.
Davriel, Rogue Shadowmage is one of the coolest making a splash. It's the epitome of a narrow-but-powerful card providing a shot in the arm to a fringe Modern deck, in this case the infamous "8-Rack." Known for being annoying as all hell to play against and notoriously streaky to play (shoutout to Tom Ross for being, well, a boss with the deck over the years), 8-Rack now has something it has never had before: a win condition and discard effect in one.
The deck suffers from the same problem a deck like Ramp faces: sometimes you draw the wrong "half" of the deck. In the case of the archetypical ramp deck, you draw the ramp spells without the payoff spells. In the case of 8-Rack, you could often the draw the discard spells without the Shrieking Affliction effects, or the other way around. You'd strip apart their hand only to lose to a few pesky creatures because you couldn't find removal.
Davriel, Rogue Shadowmage doesn't fix all the deck's problems, but it goes a long way toward making it more consistent by combining repeatable discard and a win condition that plays nicely with Ensnaring Bridge, all in one easy three-mana package.
There's nothing revolutionary here in this recent 5-0 Magic Online league list, but Liliana's Triumph is a sneaky upgrade to the deck as well, giving you an effect Modern has needed for a while (Cruel Edict et al.)—which helps you take down the Slippery Bogle and Emrakul, the Aeons Torn players of the world, while also serving as the rare instant-speed discard effect when you get to live the dream with Liliana of the Veil in play.
Oh, did I mention we're playing Liliana of the Veil? It's still as busted as ever.
All in all, War of the Spark has provided a solid boost to a fun-but-fringe Modern deck. Hope you've got your Leyline of Sanctity handy.