msem-instigator

When Allagras' Vanguard enters, create two 1/1 blue Merfolk creature tokens with “When this creature dies, draw a card, then discard a card”.

Alluring Rider must be blocked if able.
Attain {4}{G} ({4}{G}: Transform this. Spend at least three colors of mana to activate this, and only as a sorcery.)

When Almgrove Performer enters, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — You gain 3 life.

Alquyut Mount can't attack or block alone.

Whenever Alrathan Scholar deals combat damage to a player or planeswalker, draw a card.
{2}{U}: Target creature gains flying until end of turn.

Flying, prowess
Whenever an artifact you control enters, you may draw a card. If you do, discard a card.

Motivate 2 (When this creature enters, you may motivate target creature with less power than this by putting two +1/+1 counters on it.)
{1}{W}: Target creature with a +1/+1 counter on it gains lifelink until end of turn.

First mate—At least half the cards in your starting deck are lands. (If this card outside the game is your chosen first mate, you may swap it with a card in your opening hand.)
Trample
{1}, Discard a land card: Put a +1/+1 counter on Alvarez. He deals 1 damage to any target.

Trample
Each creature you control with a counter on it has trample.

Reach
When Ambush Predator enters, you may return target Horror creature card from your graveyard to your hand.
When Ambush Predator dies, exile it and create a 3/2 green Horror creature token.

Flash (You may cast this spell any time you could cast an instant.)
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Trample
As long as it's an opponent's turn, Ambushing Alligator is a blue Bird with base power and toughness 1/1 and has flying and hexproof.

When Aminatou's Adherent enters, judge target creature you control. (Honor it by putting a +1/+1 counter on it or condemn it by sacrificing it to draw a card.)
Whenever you condemn a creature, creatures you control gain menace until end of turn.

Reach, vigilance
When Amorphous Tyrant enters, another target creature you control deals damage equal to its power to target creature or planeswalker you don't control.
Evoke {G} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Flash
When Ancestral Warlord enters, it deals 1 damage to each blocking creature.

Whenever Ancient Durumderm attacks, you may return another creature you control to its owner's hand. If you do, create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)

Ward {2}
When Ancient of Lotus Lake enters, draw a card.

At the beginning of each end step, if you drew and/or discarded six or more cards this turn, return Anemothrys, Reefcrown from your graveyard to the battlefield.
Cycling {R}{G} ({R}{G}, Discard this card: Draw a card.)

Flying
Whenever Angel of the Eclipse deals combat damage, it deals that much damage to each attacking and blocking creature.
Prevent all damage that would be dealt to Angel of the Eclipse by sources you control.

Whenever Angeltouched Komodo attacks, scry 1.
Morph {1}{R} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

First strike, haste
At the beginning of each end step, if a player lost life this turn, put a +1/+1 counter on Animara, Last of the Fell.

Whenever another nontoken creature you control enters, create a 1/1 green Saproling creature token.
{1}{G}, {T}: Populate. (Create a token that's a copy of a creature token you control.)

When Anointed General enters, if you control a legendary creature, Anointed General deals 4 damage to target creature you don't control.

When Anran's Radical enters, you may discard a card. If you do, search your library for a card with mana value 5 or greater or with {X} in its mana cost, reveal it, put it into your hand, then shuffle.
{T}: Add {C}.

Flying, vigilance
Augmented — When Antigravity Agent enters, if you've spent {W}{U}{R}{B}{G} to cast spells this turn, distribute a flying counter and a vigilance counter among one or two creatures you control.