msem-instigator

Menace
Whenever Hui Zhou, the Dark Visage perseveres, you may destroy another target legendary creature. (A creature perseveres when it survives damage.)

You have no maximum hand size.
Whenever a player casts a spell, put a +1/+1 counter on Humar.
At the beginning of your upkeep, target player draws cards equal to Humar's power.

Creatures you control have “{T}: Add {C} or one mana of any of this creature's colors.”
Attain {5}{G} ({5}{G}: Transform this. Spend at least three colors of mana to activate this, and only as a sorcery.)

Trample
Whenever another nontoken creature you control dies, you may return it to the battlefield. It becomes an Aura enchantment with enchant creature you control and “Enchanted creature gets +X/+X, where X is this Aura's mana value.”

{T}, Sacrifice Ilhus, Knight of Zarad: Destroy all creatures.

Flying, hexproof, haste
Blue permanents you control have hexproof.
Whenever you activate an ability of a red permanent, you may copy that ability. If you do, choose new targets for the copy.

Flying, trample, haste
Whenever you activate an ability of a nonland permanent, you may have Ilieth, Transcendent deal 2 damage to target creature.
{2}{R}: Creatures you control get +2/+0 until end of turn.

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.

Whenever Imako, Ninefingers becomes tapped, exile the top three cards of target opponent's library face down.
You may look at cards exiled with Imako.
Sacrifice Imako: Turn all cards exiled with it face up. Exile all cards with those names from your opponent's graveyards.

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
When Imperator Namuzzar enters, search your library for an artifact or enchantment card, reveal it, put it into your hand, then shuffle.
Civilized — Lammasu you control get +2/+2 and have hexproof as long as you control an artifact, a creature, and an enchantment.

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.

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.

Hexproof
Whenever another creature you control becomes the target of a spell an opponent controls, you may submerge that creature. (To submerge a card, exile it, then put it on the battlefield face down under its owner's control as a 2/2 creature.)
{1}{U}{U}: Turn target face-down creature you control face up.

Whenever Inishtu, Desert Healer enters or attacks, surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)
At the beginning of your upkeep, if seven or more cards are in your graveyard, you may transform Inishtu.

{T}: Add {U} or {R}. Spend this mana only to cast an instant, sorcery, or Wizard spell.
Whenever you cast your second spell each turn, untap Innova.

{T}, Sacrifice a land: Destroy target land.

Inquirer, Roaming Rover attacks each combat if able.
Whenever Inquirer deals damage to an opponent, draw a card.

Flash
Deathtouch, lifelink
Whenever Irika, Wielder of Secrets deals combat damage to a player, you may pay {U/B}. If you do, you draw a card and you lose 1 life.

Indestructible
As long as your devotion to red and white is less than seven, Iroas isn't a creature.
Other creatures you control have first strike.
Whenever you attack for the first time each turn, untap all other creatures you control. After this phase, there is an additional combat phase.

Whenever you cast a noncreature spell, scry 1.
{3}{U}, Exile an instant or sorcery card from your graveyard: Draw a card.

Whenever you cast a creature or planeswalker spell, if mana produced by a nonland permanent was spent to cast it, it gains trample and haste until end of turn.
{T}: Add {R} or {G}.

Wildcast — When Ivier, Soul of the Woods enters, return target monocolored creature card from your graveyard to your hand. If mana from a nonland source was spent to cast Ivier, return that card to the battlefield instead.

Improve {1} ({1}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
Whenever Ivy Kissinger, Sharpshooter attacks, choose a creature you control. For each kind of counter among creatures you control, you may put a counter of that kind on the chosen creature.

{T}: Izahl, the Stormbringer deals 1 damage to any target.
Whenever you cast a noncreature spell, you may untap target creature you control.