msem-instigator

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

Whenever Journeying Giftbearer or another nontoken creature you control enters, create a green and white Aura enchantment token named Wild Boon attached to that creature. The token has enchant creature and “Enchanted creature gets +1/+1.”

When Joyful Deviant enters or dies, it deals 1 damage to any target.

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.

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.

Flash
Vanishing 3 (This permanent enters with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
When Judge's Decree enters, exile another target spell or nonland permanent. When Judge's Decree is no longer on the battlefield, the exiled card's owner may cast that card without paying its mana cost.

Return target creature card from a graveyard to the battlefield. Then if that card wasn't put into a graveyard from the battlefield this turn, exile it.

Menace
{1}, Discard Jund Shardseeker: Search your library for a basic Swamp or Forest card, reveal it, put it into your hand, then shuffle.

Flash
Flying
When Justiciar Overseer enters, the next 2 damage that a source of your choice would deal to you and/or permanents you control this turn is dealt to any target instead.

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

Flash
Flying

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.

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

Menace
When Kai'Zhou enters, you may have all legendary nonland permanents phase out until your next turn.
Whenever Kai'Zhou deals combat damage to a player, they sacrifice a legendary permanent.

When Kalak Culler enters, each opponent loses life equal to the number of creatures you've sacrificed this turn.
Revive—{3}{B}, Sacrifice a creature. ({3}{B}, Sacrifice a creature, 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.)

[+1]: Discard a card. If you do, each opponent discards a card and loses 1 life.
[–3]: Destroy target creature or planeswalker.
[–7]: Draw a card for each creature card and planeswalker card in all graveyards. Target opponent loses that much life.

As long as there are seven or more loyalty counters on Kalemn, she has lifelink and deathtouch.
[+2]: Kalemn deals 2 damage to each opponent.
[+1]: Kalemn deals 1 damage to target creature or planeswalker.
[–7]: For each opponent, Kalemn deals 3 damage to that player unless they discard a card. Repeat this process six times.

Enchant creature
When Kalku Initiation enters, you lose 3 life and discard a card.
Enchanted creature gets +3/+2, has ward {2}, and has “Whenever this creature deals damage to a player, draw two cards.”

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.)

Flying, haste
Ward—Pay 3 life.
The first Dragon spell you cast each turn costs {R}{R} less to cast. (This can reduce the amount of generic mana you pay.)

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.

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.)

When Kaone enters, if it was cast, exile target instant or sorcery card from your graveyard. If its mana value is less than or equal to the number of spells you've cast this turn, you may cast a copy of that spell without paying its mana cost. If you don't cast a copy this way, put the exiled card into your hand.