msem-instigator

When Humble Tamer enters, create a 1/1 white Griffin creature token with flying.

First strike
When Hunted Haunt dies, create a 1/1 black Scout creature token.

Rapport — Whenever Hunting Hound and at least one other creature you control become tapped, Hunting Hound gets +2/+0 until end of turn.

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.)

{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.)

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.

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

Ifram's Cavalier enters with two additional +1/+1 counters on it if you didn't cast it from your hand.

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

Vigilance
Once each turn, when you cast an instant, sorcery, or Elemental spell, you may put a +1/+1 counter on Ignited Vanguard.

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

Imitator of Drakes has flying as long as it has a +1/+1 counter on it.
{2}{U}: Put a +1/+1 counter on Imitator of Drakes.

Indestructible
Immortal Child can't block creatures with greater power.

At the beginning of your upkeep, if you don't control any Imps, you may pay {B}. If you do, create a 1/1 black Imp creature token.
Sacrifice a creature: Each opponent loses 1 life.

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

When Imperial Diplomats enters, if it's not a token, create a token that's a copy of it, except it has no mana cost.
{T}, Tap an untapped creature you control: Draw a card, then discard a card.

First strike
Art of war — At the beginning of your end step, if Imperial Kensai dealt damage to an opponent this turn, you may pay 1 life. If you do, put a +1/+1 counter on Imperial Kensai.

At the beginning of each upkeep you may pay {W}. If you do, tap target creature.

Whenever Implant Tinkerer or another artifact you control enters, choose one —
• Put a +1/+1 counter on that artifact.
• Implant Tinkerer deals 1 damage to any target and you gain 1 life.

Defender

When Improvisionist enters, if it was the second spell you cast this turn, exile the top card of your library. You may play that card until the end of your next turn.

Advance {3}{W}{W} (Cast this for {3}{W}{W} to advance it as it enters. {3}{W}{W}: Advance this as a sorcery.)
Whenever Inconspicuous Loxodon advances, search your library for an Equipment card, put it onto the battlefield, then shuffle.
As long as Inconspicuous Loxodon is enchanted or equipped, he's a 5/5 legendary Elephant Rogue named Agent E.

Spells and abilities you control that target Inconspicuous Sheep cost {1} less.
As long as Inconspicuous Sheep is enchanted or equipped, they're a 3/3 legendary Sheep Rogue named Agent S.

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.

When Inexperienced Martyr dies, each opponent loses 1 life.