msem-instigator

At the beginning of your end step, you may pay {W}. If you do, exile target creature you control, then return that card to the battlefield under your control.

Exile target creature or planeswalker, then exile its controller's graveyard.

Enchant land
When Unexplored Regions enters, draw a card.
Enchanted land is an artifact in addition to its other types and has “{T}: Add one mana of any color.”

Each player chooses a nonbasic card name, then searches each of their opponents' graveyards, hands, and libraries for any number of cards with the chosen name and exiles them. Each player shuffles, then draws a card for each card exiled from their hand this way.

If you would create a token, you may instead create a tapped 2/2 green Faerie Bard creature token.
Whenever one or more creature tokens you control deal combat damage to a player, that player sacrifices an artifact or enchantment.

Menace
When Depraved Archknight enters, each opponent may pay 7 life. For each player that doesn't, you draw seven cards.

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. Create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)

When this creature enters, you may exile target non-Cat creature you control. Return that card to the battlefield under its owner's control at the beginning of the next end step.
Arise {3}{W} ({3}{W}, Exile this from your graveyard as a sorcery: Create a black token copy of it that's also a Zombie and can't block.)

Flying
When Hostile Barbfly enters, you may have it consume. When you do, target creature gets -2/-2 until end of turn. (To consume, sacrifice another creature or exile a creature card from your graveyard.)

When Hila Okunos enters, look at the top six cards of your library. You may reveal an Aura or Aurashaper card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.
Whenever another nontoken Aura or Aurashaper you control enters, create a token that's a copy of it.

Deathtouch
Whenever you cast a spell, you may pay 2 life. If you do, that spell gains deathtouch. (If it becomes a permanent, it keeps deathtouch indefinitely.)

Mistwake Hydra enters with X +1/+1 counters on it.
Creatures with power less than Mistwake Hydra's power can't block it.

Enchant creature
Enchanted creature doesn't untap during its controller's untap step.

Changeling (This card is every creature type.)
As Kalyn, Wildkin Envoy enters, choose up to three non-Human creature types.
Other creatures you control with one or more of the chosen types get +1/+1.
{2}, {T}: Create a 1/1 colorless Shapeshifter creature token with changeling. Activate only outside of combat.

Flying, vigilance
Whenever one or more other creatures you control attack, those creatures get +0/+2 until end of turn.
Whenever one or more other creatures you control block, those creatures get +2/+0 until end of turn.

Once each turn, when you activate a nonmana ability, you may have Masked Servant get +1/+1 until end of turn.
{2}{W}: Untap target creature.

Equipped creature gets +2/+2.
Whenever equipped creature attacks, exile target nonland permanent defending player controls. For as long as that card remains exiled, its owner may cast it. (They still pay its costs.)
Equip {2}

Target player loses X life and you gain X life, where X is the number of permanents you control with counters on them.

Whenever you cast a spell with mana value greater than Script Jockey's power, put a +1/+1 counter on Script Jockey.

When Seishin Rageshaper enters, create a 2/2 colorless Spirit creature token.
Colorless creatures you control have haste.

When Spiritual Colpah dies, you may return target creature card from your graveyard to your hand.

{1}: Prototype Rice Thresher gets +1/-1 or -1/+1 until end of turn.

Whenever you cast a spell from exile, Promised Seeker gets +3/+3 until end of turn.
Prophecy {G} (Once each turn, you may exile a card with prophecy as you reveal it. When you do, you may cast it for its prophecy cost as long as it's exiled.)

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
When Eager Hatchling has three or more +1/+1 counters on it, remove them all and transform it.

Landfall — Whenever a land you control enters, add {G}.
{3}{G}: Target creature you control gets +2/+2 until end of turn.