msem-instigator

First mate—Your starting deck contains only cards with mana value 0, 1, or 3. (If this card outside the game is your chosen first mate, you may swap it with a card in your opening hand.)
Menace
Once each turn, when one or more sources you control deal damage, you may put a +1/+1 counter on Hugo.

Icecap Tortoise enters with three ice counters on it.
Icecap Tortoise has defender as long as it has an ice counter on it.
{1}{U}: Remove an ice counter from Icecap Tortoise.

Whenever Impetuous Impetus deals combat damage to a player, you may sacrifice a land. If you do, Impetuous Impetus deals 3 damage to that player.

This spell costs {1} less to cast for each tapped creature you control.
Whenever Incarnation of Enmity attacks, each other attacking creature gets +1/+0 until end of turn.

When Infamous Bilgecaptain enters, forebode. (Create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.)
Other Pirates you control get +1/+1.
At the beginning of your end step, you may put a Pirate card with mana value less than or equal to the number of artifacts you control from your hand onto the battlefield.

When Ink Seer dies, you draw a card, lose 1 life, and create a Treasure token.

When Inner-Eye Obscurist enters, return each other creature that isn't in Inner-Eye Obscurist's pack to their owners' hand. (Two or more creatures you control with equal power are in a pack.)

When Inquisitive Pod enters, draw a card.
Whenever you cast your second spell each turn, Inquisitive Pod gets +3/+3 until end of turn.

({T}: Add {U}.)
Interlocked Waterways enters tapped.
{U}, {T}, Reveal a blue card from your hand: Untap target creature.

At the beginning of combat on your turn, create a 1/1 blue and red Pirate creature token with haste. That token attacks this combat if able.
Whenever Intrepid Captain attacks, other attacking Pirates you control get +1/+0 until end of turn.

({T}: Add {U}.)
Inundated Sanctuary enters tapped with two sanctum counters on it.
{T}, Remove a sanctum counter from Inundated Sanctuary: Add {W} or {B}.

Activated abilities you activate cost {3} less to activate. This effect can't reduce the mana in that cost to less than one mana.
You may spend any number of colors of mana to activate attain abilities of permanents you control.

Activated abilities you activate cost {1} less to activate. This effect can't reduce the mana in that cost to less than one mana.
Attain {5}{U} ({5}{U}: Transform this. Spend at least three colors of mana to activate this, and only as a sorcery.)

Haste
When Jetskate enters, if you've drawn two or more cards this turn, it deals 2 damage to any target.
Cycling {R} ({R}, Discard this card: Draw a card.)

This spell costs {1} less to cast for each spell you cast this turn.
When Jidai Serpent enters, draw two cards.

Concord — This spell costs {2} less to cast if there are four or more card types among permanents you control.
Vigilance (Attacking doesn't cause this creature to tap.)

When Jumbo Shrimp enters or when you cycle it, destroy target noncreature permanent.
Cycling {3}{G}{G} ({3}{G}{G}, Discard this card: Draw a card.)

Whenever a creature attacks you or a planeswalker you control, put that creature on the bottom of its owner's library unless its controller pays {2}.

Flash
When Kaivilu, Ocean Warden enters, creatures your opponents control get -2/-2 and lose all abilities until end of turn.

{1}{G}: Keen Seafarer voyages. (If it isn't blocking or targeted by another spell or ability, it phases out.)
Whenever Keen Seafarer phases in, put a +1/+1 counter on it.

When Keeper of Pearls enters or a creature you control scavenges it, you gain 2 life.
Scavenge {G} ({G}, Exile this card from your graveyard: Put a number of +1/+1 counters equal to this card's power on target creature. Scavenge only as a sorcery.)

Creatures you control get +1/+0 for each color among permanents you control and have haste.
Whenever you cast a white, blue, black, or green instant or sorcery spell, copy it for each of its colors. You may choose new targets for the copies.

Concord — You may cast this spell as though it had flash if there are four or more card types among permanents you control.
When Krill-Clan Guardian enters, it fights up to one other target creature. If that creature would die this turn, return it to its owner's hand instead.

Flying
When Krothuss, Abyssal Terror dies, return all creatures to their owners' hands except for Krakens, Leviathans, Octopuses, and Serpents.
Foreshadow {6}{U}{U} (You may cast this spell for its foreshadow cost. If you do, also trigger its “dies” abilities when it enters.)