msem-instigator

Flying, trample
Harbinger of Falling Skies enters with X +1/+1 counters on it.
Whenever Harbinger of Falling Skies attacks, you may remove a +1/+1 counter from it. If you do, draw a card.

{U}, Give yourself a lore counter: Scry 1. This ability costs {2} more to activate for each lore counter you have.
{6}{U}, Remove three lore counters from yourself, Sacrifice Harbinger of Giradrus: Draw seven cards, then create two 4/4 red Dragon creature tokens with flying.

When Harpooned Bubbledomer enters, mill four cards.
Harpooned Bubbledomer gets +2/+0 and has menace as long as there are four or more card types among cards in your graveyard.

First mate—Your starting deck contains at least twelve Vehicles. (If this card outside the game is your chosen first mate, you may swap it with a card in your opening hand.)
Haste
{R}{W}, {T}: You may put a Vehicle card from your hand onto the battlefield. That Vehicle gains haste and becomes an artifact creature until end of turn.

({T}: Add {U} or {B}.)
Hazy Moorland enters tapped.
Cycling {2} ({2}, Discard this card: Draw a card.)

Whenever you cast a spell with two or more black mana symbols in its mana cost, you draw a card and you lose 1 life.

Infiltrate (Whenever one or more attacking creatures you control aren't blocked, this creature gets +1/+1 until end of turn.)
Other creatures you control have infiltrate.

When Helicos Octopus enters, scry 1. If an opponent is cursed, scry 3 instead.

When Helicos-Drowned Captain enters, create a black Aura Curse enchantment token named Marked for Death attached to target player. The token has enchant player and “At the beginning of enchanted player's upkeep, that player loses 1 life.”

Flash
Whenever another permanent dies, put a +1/+1 counter on Heyu.
{1}{G}: Heyu becomes a colorless Island land until end of turn.

When Hila Okunos enters, look at the top six cards of your library. You may reveal an Aura or Aurashaper card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.
Whenever another nontoken Aura or Aurashaper you control enters, create a token that's a copy of it.

At the beginning of your upkeep, each opponent mills cards equal to the number of card types among permanents you control.

First mate—Each nonland card in your starting deck has the same name as exactly one other card in your starting deck. (If this card outside the game is your chosen first mate, you may swap it with a card in your opening hand.)
Vigilance
Whenever you cast a spell with the same name as a card in your graveyard, draw a card.

Other Pirates you control get +1/+0.
Whenever another Pirate you control enters, Hookhand Freebooter deals 1 damage to any target.
When Hookhand Freebooter dies, create a Bullet token. (It's an artifact with “{T}, Sacrifice this artifact: It deals 1 damage to any target.)

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}.