msem-instigator

Graft 1 (This creature enters with a +1/+1 counter on it. Whenever another creature enters, you may move a +1/+1 counter from this creature onto it.)
{T}: Add {C}.

[+1]: Each opponent puts a -1/-1 counter on a creature they control.
[–1]: Exile target card in a graveyard. You gain life equal to its mana value.
[–6]: Choose a number. You draw that many cards and you lose that much life.

{3}{B}, {T}: Choose a card name. Target player reveals cards from the top of their library until they reveal a card with the chosen name. If they do, put the revealed cards into their graveyard. Otherwise, they shuffle their library.

Inquisitor's Chamber enters tapped.
{T}: Add {B}.
{B}{B}, {T}, Sacrifice another permanent: Draw a card.

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.

You may have Insipid Metamorph enter as a copy of any other creature on the battlefield, except it's 1/1.

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.

Escalate {R} (Pay this cost for each mode chosen beyond the first.)
Choose one or both —
• Untap all creatures you control.
• Take an extra turn after this one. Skip the untap step of that turn. Exile Inspire Actuality.

{2}, {T}: Put a +1/+1 counter on target creature you control.
{2}, {T}, Sacrifice Inspiring Effigy: Put a +1/+1 counter on each creature you control.

Whenever Inspiring Tactician or another permanent you control becomes the target of a spell or ability you don't control, amass Soldiers 1. (Put a +1/+1 counter on an Army you control. It's also a Soldier. If you don't control one, create an 0/0 black Soldier Army creature token first.)

Whenever you cast or copy an instant or sorcery spell this turn, Instant of Brilliance deals 1 damage to each opponent.
Copy target instant or sorcery spell you control. You may choose new targets for the copy.

At the beginning of your upkeep, reveal the top card of your library. Any opponent may have Insurgent Ballads deal damage to them equal to that card's mana value. If a player does, put that card on the bottom of your library. Otherwise, put it into your hand.

Exile the top card of your library. Until end of turn, you may play that card. If that card is an instant or sorcery card, it costs {2} less to cast this turn.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
{U}{R}: Target creature without prowess gains prowess until end of turn. Activate only if Intelligence is in your graveyard.

Whenever a +1/+1 counter is put on a creature you control, scry 1.
Each creature you control with a +1/+1 counter on it has lifelink.

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.)

Flying, ward {1}
Intisuyu's Masterpiece gets +X/+X, where X is the number of artifacts and/or enchantments you control.

Whenever you tap a land for mana, add one mana of any type that land produced.
Sacrifice Into Strange Territories: Untap up to two lands.

If a card would be put into your graveyard from anywhere, exile it instead.
If you would draw a card, return two cards from your graveyard to your hand instead. If you can't, you lose the game.

Choose one or both —
• Create two 1/1 white Soldier creature tokens. They gain haste until end of turn.
• Create an 8/0 green Scorpion creature token with trample.

When Into the Unknown enters, create two 1/1 Scout creature tokens that are all colors.
Whenever a land you control enters, if it doesn't have the same name as another land you control, put a +1/+1 counter on each creature you control.

Search your library for a Forest card, put it onto the battlefield, then shuffle.

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.

At the beginning of combat on your turn, create a 1/1 blue and red Pirate creature token with haste. That token attacks this combat if able.
Whenever Intrepid Captain attacks, other attacking Pirates you control get +1/+0 until end of turn.

({T}: Add {U}.)
Inundated Sanctuary enters tapped with two sanctum counters on it.
{T}, Remove a sanctum counter from Inundated Sanctuary: Add {W} or {B}.