msem-instigator

First strike (This creature deals combat damage before creatures without first strike.)
Whenever a creature you control becomes blocked by a creature, Itava Scourge deals 1 damage to that creature's controller.

[+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.

If an enchanted permanent you control would leave the battlefield, instead destroy one of the Auras attached to it, then that permanent phases out. (Treat it and anything attached to it as though they don't exist until its controller's next turn.)

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.

All lands gain “{T}: Add one mana of any color” and lose all other abilities.

Artifact creatures you control get +1/+1.
{U}{R}, Sacrifice an artifact: Create a 1/1 colorless Servo artifact creature token.

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.

Jara Favored gets +2/+2 as long as you've lost life this turn.

Trample, haste
Cadence (Whenever you cast a spell, if its mana value is greater than this creature's power, put a +1/+1 counter on this creature.)

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.

Enchant creature
Enchanted creature gets +3/+3, has flying, and “{1}{W}: Put a +1/+1 counter on this creature.”

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.

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.

Creatures you control have “Whenever this creature attacks, put a +1/+1 counter on target creature with lesser power.”
At the beginning of each end step, if there are five or more +1/+1 counters among creatures you control, destroy up to one target artifact or enchantment.

Hexproof
At the beginning of each end step, if an opponent was dealt 4 or more damage this turn, return target instant or sorcery card from your graveyard to your hand.

When Jinyu Mirror-Blade enters, you may exchange its base power with another target creature's base power until either leave the battlefield.

If another creature you control would die, exile it instead.
When John Furo, the Unfortunate dies, until your next end step, you may play cards exiled with John Furo.

Destroy target permanent. Trigger a death knell of any number of permanents you control.

Vigilance, haste
All creatures able to block Jormir, Who Encircles All do so.
Jormir, Who Encircles All can block any number of creatures.

Whenever Journeying Giftbearer or another nontoken creature you control enters, create a green and white Aura enchantment token named Wild Boon attached to that creature. The token has enchant creature and “Enchanted creature gets +1/+1.”

When Joyful Deviant enters or dies, it deals 1 damage to any target.