Relentless Rats

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

Flying Whenever one or more Pirates you control deal damage to your opponents, you create a Treasure token for each opponent dealt damage. (It's an artifact with "T, Sacrifice this token: Add one mana of any color.") Partner (You can have two commanders if both have partner.)

Whenever a nontoken creature is put into your graveyard from the battlefield, if this card is in your graveyard, create a 2/2 black Zombie creature token. When a creature is put into an opponent's graveyard from the battlefield, if this card is in your graveyard, exile this card.

Flying Each creature you control is a Vampire in addition to its other creature types and has "Whenever this creature deals damage to a creature, put a +1/+1 counter on this creature."

At the beginning of your upkeep, flip a coin. If you lose the flip, this artifact deals 3 damage to you. T: Add CC.

Exile target creature. Its controller gains life equal to its power.

At the beginning of your upkeep, flip a coin. If you lose the flip, this artifact deals 3 damage to you. T: Add CC.

Whenever another creature you control dies, create a Treasure token. (It's an artifact with "T, Sacrifice this token: Add one mana of any color.")