8/21/19

Chienz89's Blue-Green Merfolk

As with all Merfolk decks, this looks to pressure the opponent with cheap creatures while disrupting them, and the reason that Merfolk is back on the map is Force of Negation. Giving Modern Merfolk a Force of Will substitute is HUGE, and both Merfolk decks were packing Forces.
The green splash gives this deck Merfolk Mistbinder and Kumena's Speaker, plus Collector Ouphe out of the sideboard. That's worth having a slightly worse manabase, especially given how much Aether Vial fixes your colors already. Plus, Waterlogged Grove is great at preventing mana flood, so this deck may have wanted some of those already, making the green splash even cheaper.
This deck has enough Lords (of Atlantis or otherwise) that it doesn't take many Merfolk to pressure the opponent, and it kills surprisingly quickly as a result. Because of that, you just need one or two disrupting elements to get across the finish line, and Force of Negation, Echoing Truth, and Spreading Seas all provide that.