This deck aims to present a steady stream of threats using Risen Reef as an engine. Cards that pump out multiple elementals like Voice of Resurgence and Master of Waves can overwhelm a board state quickly. Even if a Reef isn't in play, the deck's sticky threats can confound opponents.
I believe there is a Modern version with Collected Company; this one uses Green Sun's Zenith to ramp and to find more Reefs and Voices. Other Legacy-only cards this has access to are STP for removal and Force of Will for defense, in addition to ABUR duals.
Caleb Durward played the first version I saw to a 4-1 finish on his stream. My version is 58/60 in the maindeck, with the only difference being two Brainstorm cut for 1 Titania, Protector of Argoth and 1 Gaea's Cradle. This offers some explosiveness to the deck, which often has quite a bit of mana in play due to aggressive ramping on the first two turns with 4 Hierarch and 4 GSZ. For the sideboard, I made a few more changes, opting for a Crop Rotation package to get access to Karakas due to Marit Lage's popularity at the moment. However, there may be a better build out there. Here it is:
4 Risen Reef
4 Voice of Resurgence
4 Unsettled Mariner
4 Noble Hierarch
1 Dryad Arbor
1 Titania, Protector of Argoth
4 Phantasmal Image
4 Master of Waves
3 Swords to Plowshares
4 Force of Will
3 Force of Negation
4 Green Sun's Zenith
1 Gaea's Cradle
1 Waterlogged Grove
1 Horizon Canopy
2 Cavern of Souls
3 Misty Rainforest
3 Windswept Heath
2 Flooded Strand
1 Forest
1 Plains
1 Island
1 Savannah
2 Tropical Island
1 Tundra
2 Containment Priest
1 Gaddock Teeg
1 Knight of Autumn
2 Force of Vigor
1 Collector Ouphe
2 Veil of Summer
1 Karakas
1 Bojuka Bog
1 Swords to Plowshares
1 Pithing Needle
2 Crop Rotation