msem-instigator

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.

Harmony — Target creature gains indestructible until end of turn.
When Improvising Automaton enters, harmonize. (Trigger up to one harmony of one permanent you control.)

Gestalt (When this or another creature enters under your control, you may merge it with the one in play, keeping counters and attachments. They become the permanent on top plus all abilities from under it.)
Whenever this creature attacks, target creature blocks it this combat if able.

Haste
When Inciter of Spirits Scorned enters, return target creature card with mana value 3 or less from your graveyard to the battlefield. It gains haste. Sacrifice it at the beginning of the next end step.

Haste
When Inciting Bard enters, other creatures you control get +1/+0 and gain haste until end of turn.

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.

When Indomitable Duo enters, choose up to two creature card names.
Whenever Indomitable Duo attacks, put a +1/+1 counter on each creature you control with a name chosen by Indomitable Duo.

When Infamous Bilgecaptain enters, forebode. (Create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.)
Other Pirates you control get +1/+1.
At the beginning of your end step, you may put a Pirate card with mana value less than or equal to the number of artifacts you control from your hand onto the battlefield.

When Influential Wildborn enters, proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Whenever you cast a spell, untap Inglorious Blaze.
{T}: Inglorious Blaze deals 1 damage to target player or planeswalker.

When Ink Seer dies, you draw a card, lose 1 life, and create a Treasure token.

Whenever Inkwell Daggers enters or attacks, proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)

Whenever a creature you control enters for the second time each turn, it gains haste until end of turn. You may have it get +1/+1 until end of turn.

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

Trial 3 (As you cast this spell, an opponent of your choice may pay 3 life. If they don't, they fail the trial.)
When Inspired Trialmaker enters, if the trial was failed, add {R}{W}{B}.

Harmony — Target creature gets +2/+2 until end of turn.
When Inspiring Band enters, harmonize. (Trigger up to one harmony of one permanent you control.)

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.

When Intrepid Shieldmate enters, target creature gets +1/+1 until end of turn.

Advance {4}{R} (Cast this for {4}{R} to advance it as it enters. {4}{R}: Advance this as a sorcery.)
Whenever Intruder Drone advances, exile the top card of your library. You may cast a spell exiled with Intruder Drone with mana value 3 or less without paying its mana cost.

At the beginning of your upkeep, rouse 1. Then if you control a creature with power 5 or greater, put a +1/+1 counter on each creature you control. (Put a +1/+1 counter on a permanent you control. If it isn't a creature, tap it and it becomes a 0/0 creature in addition to its other types.)

When Ironeyes Desperado is exiled from your library, you may pay {R}. If you do, cast it without paying its mana cost.
Haste

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 Irticull's Vanguard enters, exile target nonland permanent an opponent controls until Irticull's Vanguard leaves the battlefield.
Reprocess {1}{W}{W}{W} (Cast a copy of this from your graveyard by exiling it and paying {1}{W}{W}{W}. Spend only mana from differently named sources this way.)

Flying
Morph {4}{R}{W} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
When Ishim of Devilry is turned face up, put a +1/+1 counter on it, then each opponent loses 2 life and you gain 2 life.