msem-instigator

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

{1}, {T}: Put a +1/+1 counter on Jade Sentinel. Activate only if you control a creature with power greater than Jade Sentinel's.

{T}: Add {C}.
{T}: Add {C}{C}. You can't spend this mana to cast spells or activate abilities of lands.

Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{3}{G}, Sacrifice Jade Vault Reclaimer: Destroy target artifact or enchantment.

Equipped creature gets +2/+1.
Equip {2}

As long as Jadycian Empath is on the battlefield or in your graveyard, it's a land in addition to its other types.
Sacrifice Jadycian Empath: Add one mana of any color.

Jagged Cairn enters tapped.
{T}: Add {R} or {G}.
{2}{R}{G}, {T}, Sacrifice Jagged Cairn: Draw a card.

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

{1}, {T}: Tap target creature.

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.

Trample
Other creatures you control have base power and toughness 8/8.

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.)

You gain 5 life. Then draw a card if you've lost life this turn.

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

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.

Menace
Inspired — Whenever Jeering Kit becomes untapped, target Fox you control gets +1/+1 until end of turn.

Audition for green, then audition for green. (Create a 1/1 Construct Actor creature token, a Scout Role giving 2/3 and vigilance, or a Warrior Role giving 3/2 and trample. Roles replace older ones.)

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.

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.

Choose two —
• Attacking creatures target player controls get +2/+0 and gain first strike until end of turn.
• Jeska's Command deals 3 damage to target creature.
• Creatures target player controls without flying can't block this turn.
• Target player exiles the top card of their library. Until the end of their next turn, they may play that card.

[+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.”

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.)