msem-instigator

Menace
When Icilica's Icestrider enters the battlefield, choose one —
• Draw a card if you own a card in exile.
• Target player discards a card if that player owns a card in exile.

When Ikari-no-Oni enters the battlefield, other creatures you control get +1/+0 until end of turn.

Flash
Whenever Iken Company Nightwalker deals combat damage to a player, put a +1/+1 counter on it.

Sabotage — Whenever an opponent or permanent an opponent controls becomes the target of a spell you control, Iken Troubleshooter deals 2 damage to each opponent.

When Ill-Fated Seer enters the battlefield, each player sacrifices a creature. If they can't, Ill-Fated Seer deals 3 damage to them.
Revive {2}{B}{R} ({2}{B}{R}, Exile this card from your graveyard: Create a token that's a copy of this card, except it has no mana cost. Activate this ability only any time you could cast a sorcery.)

Flying
Illuminated Firebird can't block.
Foresight — Whenever you draw your second card each turn, return Illuminated Firebird from your graveyard to the battlefield.

Flying
When Illuminating Archangel enters, target creature gets +X/+X and gains vigilance and first strike until end of turn, where X is the number of permanents you control that are Angels, Demons, Faeries, and/or Spirits.

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.

Flying
When Illusionary Steed becomes the target of a spell or ability, sacrifice it.

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.

Vigilance
Imisti's Commando can't be blocked by creatures with lesser power.
Whenever Imisti's Commando deals combat damage to a player, draw a card.

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.

When Impatient Busker enters the battlefield, you may put a lore counter on target Saga.

Civilized — At the beginning of your upkeep, if you control an artifact, a creature, and an enchantment, you draw a card and you lose 1 life.

As long as Imperial Proclaimer is on the battlefield, it has all names of nonlegendary creature cards in addition to its name.

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.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Trample
Madness {2}{G} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Harmony — Target creature gains indestructible until end of turn.
When Improvising Automaton enters the battlefield, 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.

When Incense Stoker enters the battlefield, you may return target instant or sorcery card with mana value less than or equal to the number of differently named lands you control from your graveyard to your hand.

Haste
When Inciter of Spirits Scorned enters the battlefield, 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 the battlefield, other creatures you control get +1/+0 and gain haste until end of turn.

As long as Inconspicuous Platypus is enchanted or equipped, he's a 3/3 legendary Platypus Rogue named Agent P and can't be blocked.