After a year and change of fair Death's Shadow decks in Modern, it's easy to forget that the card started as the central component of a powerful combo deck, combining the one-mana threat with Temur Battle Rage and Become Immense for kills as early as turn two and often by turn four.
The banning of Gitaxian Probe made those decks significantly weaker by removing an enabler for early Death's Shadows and an easy way to fill the graveyard for delve. Without it, functioning as a pure combo deck became untenable, and we eventually moved on to Jund and then the Grixis Death's Shadow decks we know today.
But perhaps we were too quick to scrap that deck. Today's list is remarkably similar to Brad Nelson's Death's Shadow Aggro list from the 2016 Players' Championship, simply replacing the maindeck copies of Gitaxian Probe with eighteenth land, two more Lightning Bolts, and a Dismember. The added disruption makes sense given that you're going to be less reliable at combo-ing early, and the Dismember in particular adds some more life loss to the deck. And adding a land when cutting cantrips also makes perfect sense, so some obvious replacements and the deck can still compete.
What this points to is the banning of Gitaxian Probe not being the biggest factor in the deck's decline in 2017. It was the printing of Fatal Push, an excellent removal spell against Death's Shadow and other large, cheap creatures that put a damper on this one. As Fatal Push became ubiquitous last year, this deck became unplayable, but we're now back in a metagame where Lightning Bolt is on top, and even though that can make managing your life total tricky, it's a lot easier to beat than the clean answer to a 12/12.
Even if you're relying on your other creatures, Mutagenic Growth will protect them and potentially get a few more points of damage in to boot. This deck functions a lot like Infect in that respect, and that's another deck that declined after the Gitaxian Probe ban, but is seeing a resurgence now that Fatal Push isn't quite as popular as it was last year. This deck is definitely trickier to play than Infect, but I think it's more powerful and has the ability to function as a normal aggro deck more effectively, since its creatures are actually sized to rumble in combat rather than evade blockers.
With Infect returning to the Modern metagame, we should be looking out for this one to come back, too.