msem-instigator

Exile the top card of each player's library. You may play one of those cards this turn.

Flying, lifelink
Legendary creatures you control get +1/+1.

Target creature you control gets +2/+2 until end of turn. If it's blocked or blocking, it gets an additional +2/+2 until end of turn.

Whenever a nontoken creature enters under your control, create a Field land token with “{T}, Sacrifice this land: Add one mana of any color.”
Whenever a nontoken land enters under your control, create a 1/1 white Peasant creature token.

Enchant creature
Enchanted creature gets -1/-1 and can't block.
Enchanted creature gets an additional -1/-1 for each card named Garrote in your graveyard.

Flash (You may cast this spell any time you could cast an instant.)
Flying
Tapped creatures you control have hexproof.

When Scaleblight Warrior enters, you gain 2 life.
Pay 2 life: Scaleblight Warrior gains menace until end of turn.

(As an Encounter enters, choose an opponent to protect it. You and others can attack it. When defense counters are removed, create a 0/0 Army token if you don't control one, then put that many +1/+1 counters on a Army you control.)
When Avaz Rising enters, return target creature card from your graveyard to the battlefield. That creature becomes an Army in addition to its other types.

Corsair Sellsword can't block.
Whenever you foretell a card or cast a foretold spell, you may return Corsair Sellsword from your graveyard to your hand.

Dominance — If you control the creature with the greatest power or tied for the greatest power, you may pay {U} rather than pay this spell's mana cost.
Counter target spell unless its controller pays {3}.

Equipped creature gets +3/+3.
Equip {4}
Equip creature with power 5 or greater {1}

Vigilance
{W}{U}: Each creature you control assigns combat damage equal to its toughness rather than its power this turn.

Hexproof, trample
Whenever Gui, the Islandbringer deals combat damage to an opponent, reveal the top card of your library. If it's a land card, put it onto the battlefield. Otherwise, put it into your hand.

Sacrifice a creature: Pale Horse gets +2/+2 until end of turn.
Ride {B} ({B}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)

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 Hundred Years of Solitude enters, exile another target nonland permanent until Hundred Years of Solitude leaves the battlefield.

Destroy target artifact or enchantment. Surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)

Enchant opponent
When Lost Knowledge enters, enchanted player reveals their hand.
{1}, Sacrifice Lost Knowledge: Scry 2, then draw a card.

Create two 1/1 blue Bird creature tokens with flying and “When this creature dies, draw a card.”

Haste
Revive {3}{R} ({3}{R}, Exile this card from your graveyard: Create a token that's a copy of this card, except it has no mana cost. Activate this ability only any time you could cast a sorcery.)

Choose a number. Reveal that many cards from the top of your library and put them into your hand. You lose life equal to the total mana value of those cards.

When Blossom-Sower Witch enters, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
Whenever you sacrifice a permanent, you gain 1 life.

Trample
Other creatures you control have trample.
{5}{G}{G}: Creatures you control get +2/+2 until end of turn.

Haste
At the beginning of combat on your turn, create two nonlegendary token copies of Thrice-Clawed Troika. Then for each creature token created this way, create token copies of each permanent attached to Thrice-Clawed Troika and attach them to that creature token. Exile all tokens created this way at end of combat.

When Duchess Odelia VII enters, search your library for a nonland permanent card with mana value 1 or less, reveal it, put it into your hand, then shuffle.