msem-instigator

Whenever Illumination Savant attacks, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — Put a +1/+1 counter on each artifact creature and enchantment creature you control.

Flash
Trample

{G}: Exile target card from a graveyard. If a creature card with flying is exiled this way, put a flying counter on Illustrious Qilin. The same is true for first strike, double strike, deathtouch, haste, hexproof, indestructible, lifelink, menace, reach, trample, and vigilance.

Imisti enters with a concoction counter on it for each land card in your graveyard.
{1}{G}, Remove any number of concoction counters from Imisti: You gain that much life.
{3}{B}, Remove any number of concoction counters from Imisti: It deals that much damage to target creature or planeswalker.

Whenever Imisti, Elven Insurgent attacks, mill two cards. When you do, you may return target land card from your graveyard to your hand.
{X}{B}{G}: If Imisti has no +1/+1 counters on it, put X +1/+1 counters on Imisti. Activate only as a sorcery.

Flying
Whenever Immaculate Clouddasher attacks, up to three target creatures gain flying until end of turn.

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
{1}, Sacrifice another creature: Imperious Aristocrat gains indestructible until end of turn. If you're in a renaissance, each opponent loses 2 life and you gain 2 life.

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.

Flash
First strike
When Imposing Databdara enters, return each other creature with toughness less than or equal to the number of Satrapies you control to their owners' hands.

Flying
Nonland permanents your opponents control enter tapped.
Activated abilities of permanents your opponents control that entered this turn can't be activated unless they're mana abilities.

Harmony — Target creature gains indestructible until end of turn.
When Improvising Automaton enters, harmonize. (Trigger up to one harmony of one permanent you control.)

Gestalt (When this or another creature enters under your control, you may merge it with the one in play, keeping counters and attachments. They become the permanent on top plus all abilities from under it.)
Whenever this creature attacks, target creature blocks it this combat if able.

Haste
When Inciter of Spirits Scorned enters, return target creature card with mana value 3 or less from your graveyard to the battlefield. It gains haste. Sacrifice it at the beginning of the next end step.

Haste
When Inciting Bard enters, other creatures you control get +1/+0 and gain haste until end of turn.

Disgraced 1 (This enters with a -1/-1 counter. Whenever it deals combat damage to a player, remove all -1/-1 counters from it.)
Whenever Indebted Burglar becomes blocked, defending player loses 1 life.

When Indomitable Duo enters, choose up to two creature card names.
Whenever Indomitable Duo attacks, put a +1/+1 counter on each creature you control with a name chosen by Indomitable Duo.

Menace
At the beginning of your end step, if you gained or lost life this turn, put a -1/-1 counter on up to one target creature.

Flying
When Ineptitude enters, untap target creature and gain control of it until end of turn. Put three stun counters on that creature. It gets +3/+3 and gains haste 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 Influential Wildborn enters, proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Whenever you cast a spell, untap Inglorious Blaze.
{T}: Inglorious Blaze deals 1 damage to target player or planeswalker.

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

Whenever Inkwell Daggers enters or attacks, proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)

Whenever a creature you control enters for the second time each turn, it gains haste until end of turn. You may have it get +1/+1 until end of turn.

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