msem-instigator

Haste
Augmented — When Attuned Lifeform enters, 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.

Prowess
Other Monks you control get +1/+1.
Whenever you cast a spell during another player's turn, untap each Monk you control.

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.

Tribute 3 (As this creature enters, an opponent of your choice may put three +1/+1 counters on it.)
When Atuum Serpent enters, if tribute was paid, it gains defender. (This effect lasts indefinitely.)

You may put a +1/+1 counter on target creature you control. It deals damage equal to its power to another target creature or planeswalker.

{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.)

{1}, Sacrifice a creature or enchantment: Exile the top card of your library. You may play that card this turn.

Counter target spell. If you are glorious, draw a card. (You are glorious as long as you have a glory counter.)

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
When Augur of Bleak Horizons enters, you gain 3 life and you mill three cards.

Flying, vigilance
When Augur of Pathways enters, surveil 1.

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

Mill three cards. You may return a card milled this way to your hand. Each opponent loses 2 life.
Flashback {3}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Flying
Whenever August Sunbird attacks, create a token that's a copy of another target creature you control, except it's 1/1, and it's tapped and attacking. Sacrifice the token at the beginning of the next end step.

Enchant creature
When Aura of Leadership enters, create four 1/1 white Human Soldier creature tokens.
Enchanted creature gets +2/+2.

When Auramancer enters, you may return target enchantment card from your graveyard to your hand.

Target player sacrifices an enchantment.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, return up to one enchantment card from your graveyard to your hand.

When Aureate Golem enters, create a Treasure token. Each other player creates a tapped Treasure token. (They're artifacts with “{T}, Sacrifice this artifact: Add one mana of any color.”)

Counter target creature spell. Scry 2.
Foresee — As you draw Aurora's Whisper, you may reveal it and pay {U}. When you do, return target creature with mana value 3 or less to its owner's hand.

Trample
Auspicious Qilin must be blocked if able.

Exile target tapped creature. Its controller gains 3 life.

When Automated Blademaster enters, create a colorless Equipment artifact token named Sword with “Equipped creature gets +1/+1” and equip {1} and attach it to Automated Blademaster.

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

{T}: Add {C}.
{2}, {T}: Add three mana of any one color.

Creatures you control get +1/+0 and gain haste until end of turn.