msem-instigator

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.

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.

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.

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

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

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle. You gain 3 life.

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.”

Look at the top four cards of your library. You may put a land card from among them onto the battlefield tapped. Put the rest into your graveyard.

When Journey to Elrayin enters, journey, then choose a creature card name. (To journey, exile the top card of your library face up. Whenever a creature you control deals combat damage to a player, put a journeyed card you own into your hand.)
Whenever a creature you control with the chosen name deals combat damage to a player, journey.

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.)

When Journeying Packmaster enters, look at the top card of your library. If it's a land card, you may put it onto the battlefield tapped. If you didn't put that card onto the battlefield, draw a card.

As Joyous Chromatelk enters, choose a color.
All cards that aren't on the battlefield, spells, and permanents are the chosen color in addition to their other colors.
{T}: Add one mana of the chosen color.

Once each turn for each card type, when you cast a spell with that type, you may copy it. You may choose new targets for the copy. If it's a permanent spell, the copy gains haste and “At the beginning of the end step, sacrifice this permanent.”
Whenever a permanent you control dies, it deals 1 damage to each opponent.

Double strike, menace, trample
At the beginning of your end step, sacrifice Juddering Mishap unless you've cast a spell with no creature types this turn. (Noncreature spells have no creature types.)

When Judge of Clans enters, adjudicate. (Create a white enchantment Aura token with enchant creature and “Sacrifice this token: Untap enchanted creature.” attached to target creature.)
{T}: Add one mana of any color.

Judgment of Hao'Tai deals 4 damage to each non-Dragon creature.

When Jumbo Shrimp enters or when you cycle it, destroy target noncreature permanent.
Cycling {3}{G}{G} ({3}{G}{G}, Discard this card: Draw a card.)

Menace
Swampcycling {1}, forestcycling {1} ({1}, Discard this card: Search your libary for a Swamp or Forest card, reveal it, put it into your hand, then shuffle.)

When Junktrawler enters, create a tapped colorless Powercell artifact token with “{T}: Add {C}.”
Tap another untapped artifact you control: Junktrawler gets +1/+1 until end of turn.

Transcend (Activate as a sorcery to gain the next type and a +1/+1 counter.)
Jutou enters with X +1/+1 counters on her.
{3}{G}: Demigod — You gain life equal to the greatest power among creatures you control.
{6}{G}: God — Search your library for a creature card with the same power as a creature you control, put it onto the battlefield, then shuffle.

Juvenile Boa gets +2/+0 as long as you control a legendary creature.

Whenever an artifact you control becomes tapped, K-17 Drone deals 1 damage to each opponent.