msem-instigator

Whenever you gain life, put a +1/+1 counter on Faithful Acolyte.
Faithful Acolyte has lifelink as long as it has four or more +1/+1 counters on it.

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
Whenever Goldtooth Slasher attacks, you may sacrifice an artifact or creature. If you do, Goldtooth Slasher gets +2/+0 and gains lifelink until end of turn.

Enchant opponent
When Pathless Shallows enters, exile target creature enchanted player controls until Pathless Shallows leaves the battlefield.
Enchanted player can't cast spells with the same name as the exiled card.

When Sandmouth Dragon enters, another target creature you control gets +3/+0 until end of turn.
Mirage {2}{R} (You may cast this spell as though it had flash for its mirage cost. If you do, sacrifice it at the beginning of the next cleanup step.)

Archive 2 (As this enters, shuffle the top two cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
{R}{W}: Put a nontoken artifact or creature you own on the bottom of the archived library. Create a token that's a copy of it.

When Plane-Traversal Guide enters, you may exile a card you own from outside the game. When Plane-Traversal Guide is no longer on the battlefield, put the exiled card into your hand.

Kicker {U} (You may pay an additional {U} as you cast this spell.)
Flying
If Aven Ranger was kicked, it enters with a +1/+1 counter on it.

Rhapsody {4}{R}{R} (Pay {4}{R}{R} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
Double strike

Exile target card from a graveyard. If this spell was foretold, create a 2/1 white Soldier creature token.
Draw a card.
Foretell {W} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Prowess
Wither (This deals damage to creatures in the form of -1/-1 counters.)

Put a +1/+1 counter on target creature.
Flashback {1}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Target player draws seven cards, then their life total becomes equal to the number of cards in their hand.

When Shokan Captain enters, you may search your library for an Equipment card, reveal it, shuffle, then put that card on top.
Art of war — At the beginning of your end step, if Shokan Captain dealt damage to an opponent this turn, put a +1/+1 counter on it.

Mill four cards, then return a creature or enchantment card from your graveyard to you hand. You gain 3 life.

Trample
Whenever Chasqui Veteran deals combat damage to a player, if you control three or more artifacts and/or enchantments, draw a card.

Flying
When Syrina, the Dragon Queen enters, gain control of target nonland permanent for as long as you control Syrina, the Dragon Queen.
{2}{U}: Exile Syrina, the Dragon Queen. Return her to the battlefield at the beginning of the next end step.

Target creature can't be blocked this turn.
Compose (Then if you cast this from your hand, exile it and create a Saga token with “r3—You may cast a copy of this card from exile without paying its mana cost.”)

Enchant creature
Enchanted creature doesn't untap during its controller's untap step.
{2}{U}: Return Sequester to its owner's hand.

{3}: Create a 9/9 colorless Angel artifact creature token with flying and lifelink.

Flash
When Turned by Fear enters, return up to one target creature to its owner's hand.
At the beginning of combat on your turn, up to one target creature gains menace until end of turn.

Erratic (When this creature dies, reveal the top four cards of your library. Put a creature card that costs less than this revealed this way onto the battlefield and the rest on the bottom of your library in any order.)
Whenever a creature you control enters, if you didn't cast it from your hand, target land you control becomes a 7/1 red Elemental creature with trample and haste. It's still a land.

Equipped creature gets +1/+0 and has poisonous 1. (Whenever it deals combat damage to a player, that player gets a poison counter.)
Equip {1}

When Abura-no-Oni enters, target player mills two cards.

Choose one or both—
• Target creature gets -4/-4 until end of turn.
• Return target creature card with mana value 1 from your graveyard to the battlefield.

Flying
Morph {3}{G}{U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
When Ishim of Tempest is turned face up, put a +1/+1 counter on it, draw three cards, then discard two cards.