msem-instigator

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
{1}, Sacrifice another creature: Imperious Aristocrat gains indestructible until end of turn. If you're in a renaissance, each opponent loses 2 life and you gain 2 life.

Whenever Implant Tinkerer or another artifact you control enters, choose one —
• Put a +1/+1 counter on that artifact.
• Implant Tinkerer deals 1 damage to any target and you gain 1 life.

Defender

Create a 2/2 black Horror creature token.
Compose (Then if you cast this from your hand, exile it and create a Saga token with “r3—You may cast a copy of this card from exile without paying its mana cost.”)

Enchant creature
Enchanted creature can't attack, block, or be sacrificed.

You may reveal a creature card you own from outside the game and put it into your hand.
The next spell you cast this turn may be cast as though it had flash. Exile Impromptu Escapade.

Enchant creature
You may cast this spell from your graveyard if it targets a legendary creature you control.
Enchanted creature gets +2/+2 and has haste.

Flying
Vanguard — Whenever a creature you control attacks alone, it gains first strike until end of turn.

Enchant creature
Whenever enchanted creature deals combat damage to a player, exile the top card of your library. Until end of turn, you may play that card.

Trial 4 (As you cast this spell, an opponent of your choice may pay 4 life. If they don't, they fail the trial.)
Search your library for an Angel card, reveal it, put it into your hand, then shuffle. If the trial was failed, non-Angel, non-God creatures can't attack or block until your next turn.

When Incense Stoker enters, you may return target instant or sorcery card with mana value less than or equal to the number of differently named lands you control from your graveyard to your hand.

Haste
When Inciting Bard enters, other creatures you control get +1/+0 and gain haste until end of turn.

Equipped creature gets +3/+2 and must be blocked by a creature that doesn't share a color with it if able.
Equip {4}

Death knell — Return an Aura card with mana value 5 or less from your graveyard to the battlefield. (As a creature you control dies, trigger one death knell of that creature or another permanent you control.)
As long as Inconspicuous Otter is enchanted or equipped, he's a 3/4 legendary Otter Rogue named Agent O and has menace.

As a permanent you control explores an Aura, you may put it onto the battlefield attached to Inconspicuous Stowaway.
As long as Inconspicuous Stowaway is enchanted or equipped, she's a legendary 2/3 Cat Rogue named Agent C and has double strike.

When Indomitable Duo enters, choose up to two creature card names.
Whenever Indomitable Duo attacks, put a +1/+1 counter on each creature you control with a name chosen by Indomitable Duo.

Target creature you control deals damage equal to its power to target creature you don't control.
Create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)

Create three 1/1 red Human creature tokens with haste. Sacrifice those tokens at the beginning of the next end step.
Draw a card.

Flash
Enchant creature
When Ineffable Patronage enters, it deals 4 damage to up to one target attacking or blocking creature.
Enchanted creature gets +2/+2.

When Infamous Bilgecaptain enters, forebode. (Create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.)
Other Pirates you control get +1/+1.
At the beginning of your end step, you may put a Pirate card with mana value less than or equal to the number of artifacts you control from your hand onto the battlefield.

Infernal Flames deals 3 damage to target player or planeswalker.
Tether (Then if you cast this from your hand, you may exile it tethered to a creature you control. When it dies, you may cast this from exile without paying its mana cost.)

Enchant creature
Enchanted creature gets +3/+0 and has trample.
Madness {1}{R} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Whenever you cast an instant or sorcery spell, Infernal Immolator deals 2 damage to each opponent.

Whenever a creature you control with power 4 or greater deals combat damage to a player, you may draw a card.

Whenever a creature you control enters, you may have target creature get +1/+1 and gain flying until end of turn.