msem-instigator

Flying, vigilance, lifelink
Idyllic Pegasus gets +1/+0 for each artifact and/or enchantment you control.

Erratic (When this creature dies, reveal the top four cards of your library. Put a creature card that costs less than this revealed this way onto the battlefield and the rest on the bottom of your library in any order.)
Ifram's Greenfur must be blocked each combat if able.

You may put a creature card from your hand onto the battlefield. That creature gains haste. Sacrifice that creature at the beginning of the next end step.

Vigilance
When Illari, Martyrized Tyrant enters, tap all other nonbasic permanents.
Players can't untap more than one nonbasic permanent during each of their untap steps.
When Illari dies, untap all permanents you control and you gain 5 life.

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.

Exile target creature or enchantment. You gain 3 life.

First strike, vigilance
Partner with Commander Hyctaleon (When this creature enters, target player may put Commander Hyctaleon into their hand from their library, then shuffle.)
At the beginning of your upkeep, you may search your library for a Soldier card, reveal it, put it into your hand, then shuffle.

Draw three cards.
Lifecycle {3} ({3}, Discard this card: Create two tapped 1/1 colorless Elemental creature tokens.)

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.)

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.

Reach
{1}, Sacrifice a nonland permanent: Imposing Manticore deals 1 damage to each opponent.

Exile the top card of your library. Impulsive Action deals damage to any target equal to that card's mana value plus one. Until end of turn, you may play that card.

Creatures you control attacking causes their death knell to trigger.
Death knell — Indomitable Spirit gets +2/+2 and gains trample until end of turn. (As a creature you control dies, trigger one death knell of that creature or another permanent you control.)

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.

At the beginning of each end step, if a player lost 5 or more life this turn, create a 5/5 black Demon creature token with flying.

Indestructible
At the beginning of each player's upkeep, target permanent you control gains protection from everything until end of turn. Then if you control at least five permanents whose colors are exactly different color triads, you win the game.

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.)

Creatures can't attack you or planeswalkers you control unless their controller pays {X} for each of those creatures, where X is the number of attacking creatures.

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

Enchant creature (Target a creature as you cast this. This card enters attached to that creature.)
Enchanted creature gets +2/+3 and has lifelink.

{4}, {T}: Put a -1/-1 counter on target creature.
{4}, {T}: Remove a -1/-1 counter from target creature.

Whenever a creature you control dies, Insidious Terror gets +1/+0 and gains menace until end of turn.

At the beginning of your upkeep, put a lore counter on Inspirational Copse, discard your hand, then draw a card for each lore counter on Inspirational Copse.

Whenever Instability Elemental enters or you draw a card except during your draw step, target creature gets +1/+1 until end of turn.

Whenever a creature enters, it deals damage equal to its power to any target of its controller's choice.
When Interplanar Raid enters, you may aetherize target creature you control. (To aetherize, create a token that's a copy of it, then exile that token.)