MTG Mono Blue Aggro Deck by Dingus Dangus

Sacrifice this creature: Counter target instant or sorcery spell unless its controller pays {1}.

As an additional cost to cast this spell, reveal a Merfolk card from your hand or pay {3}. When this creature enters, draw a card.

You may cast this card as though it had flash if you pay {2} more to cast it. (You may cast it any time you could cast an instant.) When this creature enters, you may return target tapped creature an opponent controls to its owner's hand.

Other Merfolk get +1/+1 and have islandwalk. (They can't be blocked as long as defending player controls an Island.)

Other Merfolk creatures you control get +1/+1 and have islandwalk. (They can't be blocked as long as defending player controls an Island.)

Other Merfolk creatures you control get +1/+1. Whenever you cast a Merfolk spell, you may tap or untap target permanent.

Flying Creatures you control have "Whenever this creature becomes the target of a spell or ability for the first time each turn, counter that spell or ability."

Protection from red Elemental creatures you control get +1/+1. When this creature enters, create a number of 1/0 blue Elemental creature tokens equal to your devotion to blue. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)

At the beginning of your upkeep, you may put a charge counter on this artifact. {T}: You may put a creature card with mana value equal to the number of charge counters on this artifact from your hand onto the battlefield.

Enchant land When this Aura enters, draw a card. Enchanted land is an Island.

Return target creature to its owner's hand. Its controller loses 1 life.

Counter target spell. If the spell is countered this way, exile it with three time counters on it instead of putting it into its owner's graveyard. If it doesn't have suspend, it gains suspend. (At the beginning of its owner's upkeep, they remove a time counter. When the last is removed, they may play it without paying its mana cost. If it's a creature, it has haste.)

({T}: Add {U}.)

{T}: Add {U}. {U}, {T}: Untap target legendary permanent.

{T}: Add {U}. {1}: Return Oboro to its owner's hand.

As this land enters, choose a creature type. {T}: Add {C}. {T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.

{T}: Add {C}. {T}, Sacrifice this land: Destroy target land. Its controller may search their library for a basic land card, put it onto the battlefield, then shuffle.

{T}: Add {C}. {1}: This land becomes a 2/2 creature with all creature types until end of turn. It's still a land.

As this land enters, you may reveal a Merfolk card from your hand. If you don't, this land enters tapped. {T}: Add {W} or {U}.