msem-instigator

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.

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

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.

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

You don't lose the game for drawing from an empty library.
As long as you have seven or fewer cards in each of your libraries, you may cast spells without paying their mana costs.

When this creature enters, put two -1/-1 counters on a creature you control.
When this creature dies, put a -1/-1 counter on up to one target creature for each -1/-1 counter on this creature.

Kahroba Pureblood has trample as long as it has a counter on it.

Flying
When Kai'Dwo, Eternal Ravager enters, create seven Idol tokens. (They're artifacts with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)
Whenever you sacrifice an Idol, each opponent sacrifices a creature.

Engorge (As this enters, mill three cards, then exile a card from among the milled cards.)
Whenever an instant or sorcery card you own is exiled from anywhere, you gain 1 life.

Flying
Kai'Wej, the Desolate has indestructible as long as you control no other creatures.
{1}{B}{B}, Sacrifice two creatures: Return Kai'Wej from your graveyard to the battlefield tapped.

Creature spells you cast with power 4 or greater cost {1} less to cast.

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
When Kalime Charger enters, you may have another target creature you control gain trample until end of turn.

Prismatic — Whenever you cast a multicolored spell, if you cast it from your hand, look at the top four cards of your library. You may cast a multicolored card that's different colors and costs less from among them without paying its mana cost. Put the rest on the bottom of your library in any order.

Whenever Kalro Gritbrawler attacks, if you control a Desert or there is a Desert card in your graveyard, it gains double strike until end of turn.
Desertcycling {2} ({2}, Discard this card: Search your library for a Desert card, reveal it, and put it into your hand, then shuffle.)

Kamito Pathseeker can't block.
{3}{R}, Exile Kamito Pathseeker from your graveyard: Return target instant or sorcery card from your graveyard to your hand.

Whenever you cast a noncreature spell, you may pay {R}. If you do, untap Kamito Rageweaver.
{T}: Kamito Rageweaver deals 1 damage to target player.

Haste, prowess
Whenever Kamito Warcaster attacks, you may pay {2}{R}. If you do, create a token that's a copy of another target creature you control and that's tapped and attacking. It's a colorless Spirit in addition to its other types. Exile that token at end of combat.

Rhapsody {5}{R}{W} (Pay {5}{R}{W} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
Whenever a creature you control with power 4 or greater attacks, look at the top four cards of your library. You may cast a nonland card with mana value 3 or less from among them without paying its mana cost. Put the rest on the bottom of your library in a random order.

{T}: Kanaan Wardriver deals 1 damage to target creature you control. That creature gains haste until end of turn.

Deathtouch
When Kaneh Assassin enters, judge another target creature you control. (Honor it by putting a +1/+1 counter on it or condemn it by sacrificing it to draw a card.)

Whenever a player discards a card, put a +1/+1 counter on Karatuy.
When a player has no cards in hand, Karatuy becomes a Demon and gains flying and lifelink. This ability triggers only once.
Demoncycling {1}{B}{B} ({1}{B}{B}, Discard this card: Search your library for a Demon card, reveal it, put it into your hand, then shuffle.)

Vigilance
Whenever Kardox, Hero of Skophos attacks, mill three cards, then return a Minotaur creature card from your graveyard to the battlefield tapped and attacking.
Discard a card: Kardox gains indestructible until end of turn. Tap it.

This spell can't be countered.
Trample
Whenever an opponent draws a card except the first one they draw in each of their draw steps, put a +1/+1 counter on Kareki Magehunter.

Reach
Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{3}{G}, {T}: Kareki Stormshooter fights another target creature. If that creature has flying, Kareki Stormshooter deals damage equal to its power to that creature instead.

First strike
Revive {4}{W} ({4}{W}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)