Blue has always been the color of counterspells and card draw. It has never been the color of creatures. For the first ten to fifteen years of Magic's history, that gave the color a distinct advantage since spells were significantly more powerful than creatures on average. However, since at least the introduction of planeswalkers, creatures have caught up in power level, leaving blue to react to its new situation.
Blue control decks have still been successful in more recent formats, more so in Standard than in Modern, but blue aggressive decks are another story. They aren't that common, but when they happen, they have been great. Faeries was perhaps the first in this lineage, and since then we've seen U/W Delver and Mono-Blue Devotion as top-tier decks in Standard.
Typically, these decks rise with the printing of at least one overpowered threat that has the pieces surrounding it to make a deck work.
Faeries had Bitterblossom supported by Spellstutter Sprite, Mistbind Clique, and Cryptic Command. U/W Delver had Delver of Secrets, Snapcaster Mage, and Geist of Saint Traft supported by Ponder, Mana Leak, and Vapor Snag. Mono-Blue Devotion had Thassa, God of the Sea and Master of Waves supported by Frostburn Weird and Nightveil Specter.
In Dominaria, we have a threat that powerful enough to demand an archetype built around it. Tempest Djinn is at worst a three-mana 3/4 flier, which is already above the curve, and it only gets better as you make more land drops. The four toughness means it survives most red removal. The converted mana cost of three makes it awkward to answer for Fatal Push, and white's removal is vulnerable to counterspells that are a natural pairing with a triple-blue cost creature.
The problem? There is no natural home for the card. If you go too aggressive, you aren't maximizing its power. If you go too big, you aren't maximizing its capability for aggression. Striking that balance will be critical for making Tempest Djinn work in Standard, and today's deck does that quite well.
The curve is high enough to dodge Goblin Chainwhirler but powerful enough to force opponents into awkward spots. The artifact theme gives you access to Zahid, Djinn of the Lamp as another undercosted flier and Metallic Rebuke has a generic piece of disruption in a color that is typically lacking in that area.
It may be that we need another set to make a mono-blue deck work, but this deck is at worst on the right track, and at best a dark horse for the current Standard metagame.
- 2 Merchant's Dockhand
- 4 Walking Ballista
- 4 Aether Swooper
- 4 Merfolk Trickster
- 4 Tempest Djinn
- 2 Zahid, Djinn of the Lamp
- 24 Island