Merfolk
A Modern deck, by Roland Rivera
13th place at a tournament in Philadelphia, Pennsylvania, United States on 2018-01-28

Maindeck:

Artifacts
4 Aether Vial

Creatures
4 Cursecatcher
4 Harbinger of the Tides
4 Lord of Atlantis (Not currently legal in Modern)
4 Master of the Pearl Trident
4 Master of Waves
4 Merrow Reejerey
4 Silvergill Adept
2 Watertrap Weaver

Enchantments
4 Spreading Seas

Instants
2 Dismember

Basic Lands
12 Island

Lands
2 Cavern of Souls
4 Mutavault

Legendary Lands
1 Minamo, School at Water's Edge
1 Oboro, Palace in the Clouds

Sideboard:
4 Relic of Progenitus
3 Ceremonious Rejection
2 Dispel
2 Echoing Truth
4 Negate