Delver of Secrets. Goblin Guide. Wild Nacatl. These are three of the best aggressive one-drops ever printed. Maybe the three best. They're not flashy, but they're all well above the curve for one mana, and when you're trying to kill your opponent as quickly as possible, that's what matters most.
Nacatl and Guide have seen play in the same deck before. Various Zoo decks or Naya Burn have made room for them. We've also seen Goblin Guide with Delver in U/R Tempo/Burn hybrid strategies.
But all three of them together? That would be ridiculous. It's also incredibly ambitious to have a manabase that supports three one-drops of different colors while also splashing for enough lands with the Plains type to support the kitty.
But Modern is the format of ambitious mana. Fetchlands and shocklands make finding colors very easy, and while you're going to take a lot of damage from your lands, that's not as much of a liability in a deck that's so aggressive. So let's go for it all, shall we?
The clear home for this trifecta is Tribal Zoo. An old archetype that doesn't see much play these days, it uses powerful aggressive creatures backed up by quality burn, highlighted by Tribal Flames that can be consistently cast for four and often for the full five damage. Often blue was the splash color for that fifth point, but here it's a main focus that affords you a card that plays very well with the powerful burn spells: Snapcaster Mage.
Serum Visions plays awkwardly in an aggressive deck, but the synergy with Delver of Secrets and the ability to dig for the final burn spell or two is still valuable, and Spell Snare is a great tempo play, although the full playset seems like overkill. The overall spell count is borderline for Delver at 25, but keeping that balance between threat density and consistently transforming Delver of Secrets in one of the tougher parts of tuning and sideboarding with this deck, so I'm happy with that, especially when Snapcaster and Visions give the deck more velocity than previous iterations of the archetype.
With access to solid counterspells and Lingering Souls in the sideboard, you can shift into a less aggressive shell, which is becoming a hallmark of successful decks in recent years. One of the perks of playing all the colors is the number of options when sideboarding, so I'm not surprised to see that versatility here. It's not often you see an aggro deck have such high individual card quality, and that's going to help a lot in a format with such good cheap removal.