msem-instigator

Flash
Flying
Whenever you cast a spell during an opponent's turn, create a Weapon token. When you do, you may attach it to another target creature with flying. (It's an Equipment artifact token with equip {2} and “Equipped creature gets +1/+1”.)

Flying
When Sky-Torrent Navigator enters, forebode. If you control two or more Pirates, forebode again. (To forebode, create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.”)

Return up to one target creature to its owner's hand. Then if this spell was foretold, you may destroy all creatures.
Foretell {1}{W}{W}{U} (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.)

Enchant creature
Enchanted creature gets +1/+1 and has flying.
When Skypath Pilgrimage enters, journey twice. (Exile the top two cards of your library face up. Whenever a creature you control deals combat damage to an opponent, put a journeyed card you own into your hand.)

Skysworn Aspirant has flying as long as it's embattled. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)

Flying
Whenever an embattled creature you control deals combat damage to a player, draw a card. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)

Flying
When this creature enters, target creature gains flying until end of turn.
Arise {3}{W}{W} ({3}{W}{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.)

Whenever Skysworn Savior attacks, you may return another creature you control to its owner's hand. If you do, Skysworn Savior gets +2/+2 and gains flying until end of turn.

Lifelink
When Slaffield Work-Hauler enters, create a 0/2 white Ox creature token for each enchantment you control.
Whenever an enchantment you control enters, Oxen you control get +1/+1 until end of turn.

Menace (This creature can't be blocked except by two or more creatures.)
Whenever Slaughtered Steps Taskmaster attacks, you may sacrifice another creature. If you do, Slaughtered Steps Taskmaster gets +2/+0 until end of turn.

Identity — As long as you control at least two other creatures that share a creature type with Slicing Steer, Slicing Steer and creatures you control that share a creature type with it get +1/+0 and have menace.

Equipped creature has “{1}, {T}: This creature deals 1 damage to any target.”
Whenever equipped creature deals damage to a creature with power 5 or greater, sacrifice Sling of the Meek. If you do, destroy that creature.
Equip {3}

Exile target creature you control, then return that card to the battlefield under its owner's control.
Draw a card.
Foretell {1}{U} (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.)

Put a +1/+1 counter on up to one target creature you control. That creature can't be blocked this turn.
Draw a card.

Whenever a creature attacks you or a planeswalker you control, that creature's controller mills two cards.

(Transform this if it's not attached to a creature. Pay {2}{W} as a sorcery to unattach it.)
Enchant creature you control
Slopestrider's Chariot's rider gets +1/+1 and has double strike.

Equipped creature gets +2/+1.
Whenever equipped creature blocks or becomes blocked by a creature, it deals 2 damage to that creature.
Equip {2}

When Smuggler of the Santriza enters, you may discard a card. If you do, draw a card.

Target nonland permanent's owner puts it on the top or bottom of their library.

Equipped creature gets +1/+1.
Whenever equipped creature attacks, create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)
Equip {2}

Flash
Flying
Whenever this creature enters or you cast a spell during an opponent's turn, you may exile target non-Cat permanent you control, then return that permanent to the battlefield tapped under its owner's control.

Flying

Whenever you cast a noncreature spell, this creature gets +1/+0 and gains first strike until end of turn. Surveil 1.

When Sofia's Swashbucklers enters, you may return target card with foretell from your graveyard to your hand.

Foretell {B}{R} (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.)
Haste
Whenever Sofia deals combat damage to an opponent, exile the top card of that player's library face down and look at it. You may play that card for as long as it remains exiled, and you may spend mana as though it were mana of any type to cast that spell. Then foretell Sofia. It costs {0} to foretell this way.