msem-instigator

Flying, vigilance

Enchant creature
Harness (You may tap a creature you control as you cast this spell. If you do, reduce this spell's mana cost by that creature's power.)
Enchanted creature doesn't untap during its controller's untap step.

Enchant creature
When Hypnotic Halo enters, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)
{2}{W}{W}, Sacrifice Hypnotic Halo: Exile enchanted creature.

Whenever IG-2 Disassembler enters or attacks, you may sacrifice an artifact. When you do, IG-2 Disassembler deals 2 damage to target player or planeswalker.

Enchant artifact or creature
Enchanted permanent doesn't untap during its controller's untap step.

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.

When Ichi-no-Oni enters, each player loses 2 life.

Target creature gets -2/-1 and gains winnow until end of turn. (Damage dealt to it also causes its controller to lose that much life.)

{T}: Add one mana of any color. You can't spend this mana to cast spells with mana value 3 or greater.
Revive {2}{G} ({2}{G}, 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.)

Menace
When Icilica's Icestrider enters, 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 Ideologize enters, exile target creature an opponent controls and each other permanent with the same name that player controls. When Ideologize is no longer on the battlefield, return a card exiled with it to the battlefield under its owner's control.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
When Idleglen Instructor enters, draw a card, then discard a card.

Flying
Whenever Idol of the Dead God deals combat damage to a player, search your library for any number of creature cards named Idol of the Dead God, reveal them, put them into your hand, then shuffle.

Haste
Ifram's Emissary gets +1/+1 as long as you control a green or blue permanent.

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.

Target creature gets +2/+0 and gains first strike until end of turn. If it's attacking a battle, it gains double strike until end of turn.

{R}: Igniting Lavaling gets +1/+0 until end of turn.
{4}{R}, Sacrifice Igniting Lavaling: It deals 3 damage to any target.

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

Target player sacrifices an attacking or blocking creature.

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

Search your library for a basic land card, reveal it, put it into your hand, then shuffle. Mill three cards.

Enchant creature
Enchanted creature gets +2/+0 and has first strike.
Mirage {R} (You may cast this spell as though it had flash for its mirage cost. If you do, sacrifice it at the beginning of the next cleanup step.)

Each opponent sacrifices a creature or planeswalker. If you own a foretold card in exile, you gain 4 life.

Distribute three +1/+1 counters among any number of creatures you control.
Metamorph {1}{G} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up and cast it at any time for its metamorph cost.)

At the beginning of each opponent's end step, that player gets a poison counter unless damage was dealt this turn.