msem-instigator

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.

When Imperial Artisan enters, draw three cards, then put two cards from your hand on top of your library in any order.

{U}, Sacrifice Imperious Nixie: Return target creature to its owner's hand.

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.)

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.

Death knell — Return an Aura card with mana value 5 or less from your graveyard to the battlefield. (As a creature you control dies, trigger one death knell of that creature or another permanent you control.)
As long as Inconspicuous Otter is enchanted or equipped, he's a 3/4 legendary Otter Rogue named Agent O and has menace.

As a permanent you control explores an Aura, you may put it onto the battlefield attached to Inconspicuous Stowaway.
As long as Inconspicuous Stowaway is enchanted or equipped, she's a legendary 2/3 Cat Rogue named Agent C and has double strike.

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.

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.

Whenever Infernal Barrier is dealt damage, it deals 1 damage to each opponent.

{T}: Add one mana of any color.
Whenever you tap Ingrained Virago for mana, each opponent loses 1 life.

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.

{2}{B}, Sacrifice Innocuous Sidekick and another creature: Create a 4/4 black Horror creature token with menace. Activate only as a sorcery.

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

Whenever Insatiable Abomination or another Horror you control enters, each player mills four cards.
Exile a creature card from your graveyard: Tap target Horror you control. It gains indestructible until end of turn.

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

{1}{W}, {T}: Tap target creature.
Put a -1/-1 counter on Insistent Ingenue: Untap Insistent Ingenue.

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

Flying
When Intrepid enters, search your library for a land card, reveal it, put it into your hand, then shuffle.
Wanderlust — {0}: Intrepid becomes an artifact creature until end of turn. Activate only if you control four or more differently named lands.

Other Vampires you control get +1/+1.
Whenever Irascible Bloodwitch or another Vampire enters under your control, Irascible Bloodwitch deals 1 damage to any target.

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

Embellish {3}{R}{R} (If you cast this spell for {3}{R}{R}, create a 1/1 blue Thopter artifact creature token with flying when it enters.)
Desecrate (When this creature enters, you may sacrifice an artifact or land.)
When Ironsmash Drill-Delver desecrates a permanent, it deals 3 damage to any target.

When Irrigation Trawler enters, reveal the top card of your library. If that card was a land card, put that card into your hand. Otherwise, create a colorless artifact token named Lotus Petal with “{T}, Sacrifice this artifact: Add one mana of any color.”