msem-instigator

Menace
Whenever Issbarren Creeper deals combat damage to a player, draw a card, then discard a card.

Flying, haste
Dominance — At the beginning of combat on your turn, if you control the creature with the greatest power or tied for the greatest power, you may pay {1}{R}. If you do, return Issbarren Phoenix from your graveyard to the battlefield.

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.

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.

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}.

Deathtouch
As long as there are five or more different creature types among creatures you control, Itinerant Stalker gets +1/+0 and must be blocked if able.

When Jaakuna Bloodsworn enters, any opponent may have it deal 3 damage to them. If a player does, sacrifice Jaakuna Bloodsworn.

Double strike
Art of war — At the beginning of your end step, if Jaakuna Tyrant dealt damage to an opponent this turn, put a +1/+1 counter on it.

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

({T}: Add {R} or {W}.)
Jagged Crag enters tapped.

Equipped creature gets +2/+0 and has “{T}, Unattach Javelin: It deals 2 damage to target creature.”
Equip {2}

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

Advance {2} (Cast this for {2} to advance it as it enters. {2}: Advance this as a sorcery.)
Equipped creature gets +X/+0 and has flying, where X is the number of times it and Jet Pack have advanced this turn.
Equip {1}

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.)

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

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.

Choose two. You may choose the same mode twice —
• Create a 1/1 green Insect creature token.
• Put a +1/+1 counter on target creature you control.

Creatures you control get +1/+1 and gain flying and lifelink until end of turn.

Trample
{1}{R}: Each attacking creature you control with trample gets +1/+0 until end of turn.

When Journey through Kitasan enters, draw a card, then choose a creature card name.
{1}{W}: Put a +1/+1 counter on each creature you control with the chosen name. Activate only as a sorcery.

When Journey through Masamori enters, draw a card, then choose a creature card name.
Creatures you control with the chosen name have “{T}: Add one mana of any color.”

When Journey through Moranai enters, draw a card, then choose a creature card name.
Creatures you control with the chosen name have haste and “{R}: This creature gets +1/+0 until end of turn.”

When Journey through Odaya enters, draw a card, then choose a creature card name.
Creatures you control with the chosen name can't be blocked.

When Journey through Uwaito enters, draw a card, then choose a creature card name.
Whenever a creature you control with the chosen name dies, each opponent discards a card.

When Journey to the Otherworlds enters, draw a card, then choose a creature card name.
Whenever a creature you control with the chosen name attacks, you may aetherize it. (To aetherize, create a token that's a copy of it, then exile that token.)