msem-instigator

Menace (This creature can't be blocked except by two or more creatures.)
Whenever a creature you control deals combat damage to a player, you may have Aspect of Rage deal 1 damage to any target.

Whenever Aspiring Hero attacks alone, put a +1/+1 counter on it.
When Aspiring Hero dies, each opponent gains life equal to its power.

When you cast your third noncreature spell each turn, transform Aspiring Rascals.

Menace
Once during each of your turns, when you sacrifice a permanent, you may put a +1/+1 counter on Assimilated Runner.

Ward—Exile three cards from your graveyard. (Whenever this permanent becomes the target of a spell or ability an opponent controls, counter it unless that player exiles three cards from their graveyard.)
Menagerie — Astralhorn Familiar gets +2/+2 as long as there are five or more creature types among creatures you control.

When Astrid, Disgruntled Princess enters the battlefield, destroy target creature with mana value less than or equal to the number of Warriors you control.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Flying
When Atieh's Elite enters the battlefield, judge another 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 honor a creature, until end of turn, that creature has base power and toughness 4/4, gains flying, and becomes an Angel in addition to its other types.

When Attuned Ancient enters the battlefield, if you control a legendary creature, you may have Attuned Ancient deal damage equal to its power to target creature an opponent controls.

Haste
Augmented — When Attuned Lifeform enters the battlefield, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, put a +1/+1 counter on each creature you control. They gain vigilance until end of turn.

Haste
Augmented — At the beginning of combat on your turn, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, gain control of target nonland permanent until end of turn. Untap it. It gains haste until end of turn.

{2}{W}: Audacious Knight gains first strike and vigilance until end of turn. (It deals combat damage before creatures without first strike. Attacking does not cause it to tap.)

When Augmented Alchemist enters or dies, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)

Flying
Other creatures you control with flying get +1/+1.

Menace, haste
At the beginning of combat on your turn, gain control of up to two target noncreature, nonland permanents your opponents control until end of turn. Untap those permanents. You may attach any number of Equipment among them to creatures you control until end of turn. (They unattach at end of turn.)

This spell can't be countered.
Hexproof

Distorted (This creature can be blocked by tapped creatures but not untapped creatures.)
During each of your turns, you may cast an instant or sorcery spell from your graveyard. If that spell would be put into your graveyard, exile it instead.
Whenever Aurora, Soulweaver attacks, untap any number of target creatures.

When Autumnal Resonants enters the battlefield, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — Create a 3/3 red and green Elemental creature token with haste.

Trample
Harmony — Avalanche Drummer deals 1 damage to any target.
When Avalanche Drummer enters the battlefield, harmonize. (Trigger up to one harmony of a permanent you control.)

Frenzy 2 (Whenever this creature attacks and isn't blocked, it gets +2/+0 until end of turn.)
Blocked creatures you control have first strike.

Menace (This creature can't be blocked except by two or more creatures.)
Avatar of Basat can't block.

First strike
When Avaz Cataphract enters the battlefield, judge another target creature you control. (Honor it by putting a +1/+1 counter on it or condemn it by sacrificing it to draw a card.)

Flying
When Aven Strategist enters the battlefield, return up to one target creature to its owner's hand.

Trample
Whenever a player casts a noncreature spell, that player sacrifices a noncreature permanent.

When Azure Archaeologist enters the battlefield, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
{2}, {T}, Sacrifice a Clue: Draw two cards, then discard a card.