msem-instigator

[+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.

Flash
Deathtouch, lifelink
Whenever Irika, Wielder of Secrets deals combat damage to a player, you may pay {U/B}. If you do, you draw a card and you lose 1 life.

Indestructible
As long as your devotion to red and white is less than seven, Iroas isn't a creature.
Other creatures you control have first strike.
Whenever you attack for the first time each turn, untap all other creatures you control. After this phase, there is an additional combat phase.

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.

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

Whenever you cast a creature or planeswalker spell, if mana produced by a nonland permanent was spent to cast it, it gains trample and haste until end of turn.
{T}: Add {R} or {G}.

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.

Wildcast — When Ivier, Soul of the Woods enters, return target monocolored creature card from your graveyard to your hand. If mana from a nonland source was spent to cast Ivier, return that card to the battlefield instead.

Improve {1} ({1}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
Whenever Ivy Kissinger, Sharpshooter attacks, choose a creature you control. For each kind of counter among creatures you control, you may put a counter of that kind on the chosen creature.

{T}: Izahl, the Stormbringer deals 1 damage to any target.
Whenever you cast a noncreature spell, you may untap target creature you control.

[+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.

Vigilance
Augmented — Whenever Jacque attacks, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, you may exile any number of target nonland permanents, then return them to the battlefield tapped under their owners' control.

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.)

Whenever Jak, Daring Vanguard or another legendary creature you control enters, creatures you control get +1/+0 and gain haste until end of turn.

Flying, trample
At the beginning of combat on your turn, goad all creatures with power 3 or less. (Until your next turn, that creature attacks each combat if able and attacks a player other than you if able.)
Whenever a creature deals combat damage to an opponent, put a +1/+1 counter on it.

Activated abilities you activate cost {1} less to activate. This effect can't reduce the mana in that cost to less than one mana.
Attain {5}{U} ({5}{U}: Transform this. Spend at least three colors of mana to activate this, and only as a sorcery.)

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

Enspirit (As you cast this spell, you may exile a nonenchantment creature you control until this leaves the battlefield or fails to resolve. Reduce this spell's cost by the exiled card's mana value.)
{T}: The next creature spell you cast this turn has enspirit. When that creature enters, it becomes an enchantment in addition to its other types.

Once each turn, when Jeffery enters or you create an Aura token, you may create an Aura Role enchantment token named Lead Role attached to target creature you control. It's all colors and has enchant creature you control and “Enchanted creature has base power and toughness 5/5, is all creature types, and has flying, vigilance, trample, lifelink, and prowess.”
Whenever an enchanted creature you control attacks, draw a card.

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.

Flying
Once during each of your turns, for each creature you control, you may activate one of that creature's activated abilities with {T} in its cost without paying {T} and as though that creature had haste.

Whenever a creature you control enters, put a loyalty counter on Jenn, the Rising Dawn.
[0]: Target creature you control gets +1/+1 and gains first strike and lifelink until end of turn.
[–5]: Exile target creature.

Lifelink
Whenever Jerrold, Fugitive or another creature you control enters, if you cast it, you may cast target instant or sorcery card from your graveyard with lesser mana value by paying life equal to its mana value rather than paying its mana cost. Exile that card instead of putting it anywhere else as it resolves.