msem-instigator

When Ion Field enters, target player creates two 1/1 red Elemental creature tokens.
Whenever you cast an instant or sorcery spell that targets only one target, you may pay {1}{R}{R} and sacrifice Ion Field. If you do, copy that spell for each other target it could target. Each copy targets a different one of those targets.

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.

If you've lost life this turn, you may cast this spell as though it had flash.
Irate Retribution deals X damage to each creature and each planeswalker. You gain X life.

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

Trample
At the beginning of each combat, you may have Ironhide Bellower deal 3 damage to target creature you control. If you do, Ironhide Bellower gets +3/+0 and can't be blocked by creatures with total power 3 or less 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.

Flash
As long as Iroshi entered this turn, you may activate their loyalty abilities any time you could cast an instant.
[+1]: You may return a creature you control to its owner's hand. If you do, draw a card.
[–1]: Create a 2/2 green Ninja creature token.
[–2]: Target creature you control deals damage equal to its power to target creature or planeswalker.

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 {1}{U} (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 the Mists is turned face up, turn all other face-up creature you control face down.

Whenever you cast a noncreature spell, scry 1.
{3}{U}, Exile an instant or sorcery card from your graveyard: Draw a card.

Take an extra turn after this one. At any time during that turn, you may search your opponents' libraries for a card and exile it, then shuffle that player's library. You may cast that card from exile, and you may spend mana as though it were mana of any type to cast it. If you don't, shuffle that card into its owner's library.
Exile Isles Uncharted.

Trample
Augmented — Whenever you cast a spell, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, put a +1/+1 counter on Isolated Guardian. It loses this ability and gains “Whenever this attacks, put two +1/+1 counters on each of up to two target creatures.”

Menace (This creature can't be blocked except by two or more creatures.)
Swampcycling {2} ({2}, Discard this card: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.)

Trample, vigilance
You may cast Iteration Devourer from your graveyard by exiling seven other cards from your graveyard in addition to paying its other costs.

Once during each of your turns, when you cast an instant or sorcery spell, you may create a Function token with that spell's effects. (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell. A spell's effects includes added functions.)

Tap an untapped creature you control: Put a loyalty counter on Ivenge, False God. Activate only once each turn.
[+1]: Exile up to one target non-Plains permanent. At the beginning of that card's owner's next upkeep, return it to the battlefield under their control.
[–2]: Exile target nonland permanent an opponent controls. They create a Plains token. (It's a basic land with “{T}: Add {W}.”)
[–10]: Exile all permanents your opponents control. For each permanent exiled this way, its controller creates a colorless Plains basic land token.

Whenever you cast a white spell, choose up to X, where X is the number of white mana symbols in that spell's mana cost —
• Return target creature card with mana value 1 or less from your graveyard to the battlefield.
• Creatures target player controls get +1/+1 until end of turn.
• Target player gains 2 life.
• Tap target creature.

Menace
Augmented — Whenever you cast a spell, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, put a +1/+1 counter on Jaded Guardian. It loses this ability and gains “Whenever this creature attacks, defending player sacrifices two permanents.”

When Jahan, the Third Shah enters, shuffle your hand and graveyard into your library, then draw three cards.
Monument {3}{U}{U} (You may cast this transformed from your graveyard for its monument cost. Exile it if it would leave the battlefield or not resolve.)

Lionize {2}{B} ({2}{B}, Exile this card from your hand: Put a +1/+1 counter on target creature and it gains the following abilities until end of turn. You may cast this card on a later turn from exile.)
Flying
Sacrifice a creature: Put a +1/+1 counter on this creature and tap it. Any player may activate this ability.

Trample
Other creatures you control have base power and toughness 8/8.

Trample
Whenever a creature card is put into your graveyard from anywhere, put a +1/+1 counter on Jawbone, Ravenous Mutant.

Bloodprice {B}{B}{B}{B} (You may cast this card by sacrificing a creature and paying its bloodprice.)
Lifelink, haste
Sacrifice another Demon: Jejun, Dark Hunter gains flying and indestructible until end of turn.

Motley — This spell costs {3} less to cast as long as there are five or more names among nonland permanents you control.
Destroy all creatures.

Choose two —
• Attacking creatures target player controls get +2/+0 and gain first strike until end of turn.
• Jeska's Command deals 3 damage to target creature.
• Creatures target player controls without flying can't block this turn.
• Target player exiles the top card of their library. Until the end of their next turn, they may play that card.