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.

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.

Codex — Little Pig; Charging Cassowary; The Lonely Hunter; Shadowlurk; Blood Constrictor. (As this enters, conjure its contents into a shuffled face-up additional library.)
You may cast Adventures of this codex's contents from your graveyard.

[+1]: Create a tapped 3/3 black Crocodile creature token with menace.
[–1]: You may cast a copy of Size Up.
[–7]: Each land you control becomes a 3/3 Crocodile creature and gains menace and haste until end of turn.

Choose one —
• Ire of Ancient Tomes deals 2 damage to any target.
• Target instant or sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost.

Target creature you control deals damage equal to its power to another target creature.
Agonize (You may cast this card from your graveyard by putting a -1/-1 counter on a creature you control in addition to paying its other costs. Then exile this card.)

Target creature you control gets +2/+2 until end of turn. If it's blocked or blocking, it gets an additional +2/+2 until end of turn.

{T}: Add {C}.
{1}, {T}: Add one mana of any color.

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 Irreverent Sinscape enters, destroy up to one other target nonland permanent.
When Irreverent Sinscape dies, exile it. When you do, you may exile any number of cards from your graveyard that have four or more card types among them. If you do, return a permanent card from a graveyard to the battlefield under your control. You may repeat this process any number of times.

Enchant land
Enchanted land has “{T}: Draw a card, then discard a card.”

Whenever a creature you control dies, each opponent loses 1 life and you gain 1 life.
{2}{W}{B}: Ishim's Meddling becomes a 4/4 Angel creature with flying and vigilance until end of turn.

Creatures your opponents control get -4/-0 until end of turn. Scry 1. (To scry 1, look at the top card of your library. You may put that card on the bottom of your library.)

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.

As Isochron Wand enters, you may exile an instant or sorcery card with mana value 1 from your hand.
At the beginning of your upkeep, you may copy the exiled card. If you do, you may cast the copy without paying its mana cost if the spell's mana value is 1.

Enchant permanent
Enchanted permanent loses all abilities except for mana abilities and has no name.

({T}: Add {G}.)
Isolated Cloister enters tapped.
{G}, {T}, Reveal a green card from your hand: You gain 1 life.

Counter target creature spell or target spell that targets a creature an opponent controls.

Artifact creatures you control get +1/+1.
{1}{U}, Discard an artifact card: Search your library for an artifact card, reveal it, put it into your hand, then shuffle.

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.

[+2]: You may draw a card. If you don't, create a Treasure token. Repeat this process once.
[0]: Iviana deals X damage to each creature you don't control, where X is 2 plus twice the number of Dragons you control.
[–3]: Create a 5/5 red Dragon creature token with flying and haste.

[+2]: Sacrifice a creature. If you do, you may draw two cards.
[–1]: Gain control of target creature for as long as you control Jachsechep, God's Wife.
[–10]: You get an emblem with “Whenever a creature enters under an opponent's control, gain control of it.”

Sacrifice two lands, Mill five cards: Return Jack, Horrific Harvester from your graveyard to your hand.
[+1]: You gain 2 life and each opponent loses 2 life.
[–2]: Return up to one target creature card and up to one target land card from your graveyard to your hand.
[–2]: Each opponent sacrifices the nonland permanent they control with the greatest mana value among permanents they control.