Merfolk
A Legacy deck, by Tomoharu Saito
1st place at a tournament in Columbus, Ohio, United States on 2010-08-01
As reported at http://www.wizards.com/magic/magazine/article.aspx?x=mtg/daily/eventcoverage/gpcol10/welcome

Maindeck:

Artifacts
4 Aether Vial

Creatures
4 Coralhelm Commander
4 Cursecatcher
4 Lord of Atlantis
4 Merrow Reejerey
4 Silvergill Adept

Enchantments
4 Standstill

Instants
4 Daze
4 Force of Will
3 Spell Pierce

Basic Lands
2 Island

Lands
2 Flooded Strand
2 Misty Rainforest
4 Mutavault
1 Polluted Delta
2 Scalding Tarn
4 Underground Sea
4 Wasteland

Sideboard:
3 Tormod's Crypt
4 Engineered Plague
3 Submerge
2 Umezawa's Jitte
2 Nature's Ruin
1 Perish