msem-instigator

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.

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.

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.

When Jerrold's Wretched Cure enters, search your library for a legendary green card, reveal it, put it into your hand, then shuffle.
At the beginning of your upkeep, up to one other target nonland permanent you control becomes an X/X Construct creature in addition to its other types until end of turn, where X is the number of card types among cards in your graveyard.

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.

[+2]: Up to one target creature gets +1/+0 and gains first strike and haste until end of turn.
[–3]: Jeska deals 3 damage to target creature. If that creature is an artifact, she deals 5 damage instead.
[–10]: You get an emblem with “Creatures you control get +2/+0.” and “All creatures have haste and can't block.”

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.

Haste
When Jetskate enters, if you've drawn two or more cards this turn, it deals 2 damage to any target.
Cycling {R} ({R}, Discard this card: Draw a card.)

Reach
Whenever another creature you control becomes the target of an instant or sorcery spell, that creature gets +3/+3 until end of turn.

Renown 1
Whenever a creature you control becomes renowned, exile the top card of your library. You may play that card this turn.

Players play with the top card of their libraries revealed.
At the beginning of your first main phase, add {G}{G} for each land card among cards on top of libraries.
Jindao, the Coiled Prophet gets +2/+2 for each creature card among cards on top of libraries.

You may look at the top card of your library any time.
Once during each of your turns, you may play a land from the top of your library as though you could play an additional land.
{3}{G}{G}: You may cast the top card of your library without paying its mana cost if it's a creature card. Activate only as a sorcery.

You may play lands from graveyards.
{9}{G}{G}: Put nine +1/+1 counters on Jirada, Elder of Caulte.

Other attacking Foxes you control get +1/+0.
{2}{R}, Sacrifice Jiu: Discard your hand, then draw a card for each tapped Fox you control.

Whenever one or more creatures deal combat damage to you, put a -1/-1 counter on one of them.
Attain {5}{W} ({5}{W}: Transform this. Spend at least three colors of mana to activate this, and only as a sorcery.)

Indestructible
At the beginning of combat on your turn, you may untap target land you control. If you do, that land becomes an X/X green Beast creature with haste until end of turn, where X is the number of differently named lands you control. It's still a land.

When Jobiah, Devoted Farmer enters, search your library for a land card, put it onto the battlefield tapped, then shuffle.
At the beginning of your upkeep, if you control six or more lands with different names, you may transform Jobiah.

Johanna, Skarvith Marshal has first strike as long as it's attacking.
Whenever you attack, you may pay {X}{R/W}{R/W}. When you do, put a +1/+1 counter on each of up to X target attacking creatures. Those creatures gain first strike until end of turn.

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.

Enchant creature
When Join the Pack enters, create a 2/2 green Wolf creature token.
Enchanted creature gets +2/+2.

Menace, lifelink
Whenever Jonah of the Spellbane deals combat damage to a player, destroy target creature or planeswalker, then scry 1.

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

When Journey through Kareki enters, draw a card, then choose a creature card name.
Creatures you control with the chosen name get +1/+1.