Welcome to Modern Merfolk, one of the oldest decks in all of Magic the Gathering. Modern Merfolk, or Fish, is a tempo deck which swarms the board and backs up the tribe with counter magic and denial.
DECK TECH
These cards are the very core of the deck, little room for dispute here.
MutavaultThis land is amazing and should be in every build. This card a powerful enough to win games on its own, let alone if you have a lord out. This is a true tempo card, being able to both tap for mana and attack when you don't need to cast anything. This card is a great clock against control decks and it is also able to block those pesky Etched Champions.
CursecatcherThis guy is insane. He is a 1-drop so he helps to smooth out our curve, he is a beater with a few lords, and he counters things! He is really fun when you have an untapped Aether Vial with one counter on it, after your opponent plays a spell and is tapped out you can send this guy in to counter the spell.
Silvergill AdeptWhile the additional casting cost may seen bad it is not. You have so many other fish that you will rarely be without one to reveal. Being the only draw spell in the average Merfolk deck, this creature really helps you to increase your tempo.
Lord of Atlantis and Master of the Pearl TridentThese guys are amazing and still are the best lords merfolk has. Costing a mere UU, you are should to get your worth from them and because islands are so common there is a great chance of all your fish becoming unblockable, which could allow you to end the game very quickly.
Merrow ReejereyThe final fish in the core. Being that he costs 3 mana he is often not run as a 4-of to make room for other cards. He is very fun when there are multiples on the board because he allows you to play your merfolk for free, or if you want to you could tap your opponent's creatures to swing for game.
Aether VialThis card is just downright insane in this deck. Being able to keep up mana open for counters each turn while playing uncounterable creature is just absurd. And that is not all it does, there are also a lot of tricks you can pull off with one of these.
This is where things get tricky, the remaining cards are often the most changed. This version of the deck is a devotion type deck, opting for a bit higher cmc cards, to add inevitability.
Phantasmal ImageNot only is it somtimes a $4 Tarmogoyf, Image can help add to almost any board state (besides an empty one)
Spell PierceA great, cheap counter. It is great in the current meta because of all the combo decks and removal.
Vapor SnagA bounce spell that can remove blockers, or help your fish dodge removal.
Spreading SeasA great card to insure islandwalk and it also draws you a card. It is also useful for taking card of troublesome lands. Don't forget it adds to our devotion to help boost Master of Waves and Thassa, God of the Sea.
Master of Waves Controls current standard, and is now making waves in Modern. This curve topper dodges most removal in the format (sans Path to Exile). While he himself benefits from Merfolk anthems, his tokens do not, but he makes up for this by boosting our Mutavault. (Phantasmal Image copying Master of the Waves is not something any opponent likes to hear)
Thassa, God of the Sea Again, this card is moving from Standard to Modern. This helps solidify our draws late game, becoming a creature is just a bonus. Remember that you can scry before decided to add a counter to Aether Vial!!
Sygg, River Cutthroat
A body that gets around Bolt, and an incredible card advantage engine versus decks that fetch then shock.
Kira, Great Glass-SpinnerHelps protect your fishies while swinging in for 2 on her own. Be aware, she counters your own [vapor snag] !!