msem-instigator

I, II — Mill two cards. You gain 2 life. (Put the top two cards of your library into your graveyard.)
Discovery — During each of your turns, you may cast a permanent spell from your graveyard.

{T}: Add {C}.
{2}, {T}, Sacrifice Shifting Frontiers: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Chosen one ({W}{U}{B}{R}{G}: Transform this permanent.)
Whenever you cast an instant or sorcery spell, scry 1, then Horizon Augur gets +1/+1 until end of turn.

Put a +1/+1 counter on each creature you control. If this spell was cast from a graveyard, those creatures gain flying until end of turn.
Flashback {5}{W}{W} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

{T}: Add {C}.
Tap an untapped creature you control: Kurayami Shrine becomes a 1/1 Spirit creature with deathtouch until end of turn. It's still a land.

Whenever Infernal Barrier is dealt damage, it deals 1 damage to each opponent.

At the beginning of each end step, create X 1/1 white Spirit creature tokens with flying, where X is the number of nontoken creatures that died this turn.

Untap target creature you control. It gets +4/+4 and gains reach until end of turn.

Enchant creature
Enchanted creature gets -3/-0 and can't block.

When Briarform Apothecary enters, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
Sacrifice a token: Briarform Apothecary gets +2/+2 until end of turn.

{8}: Create eight 1/1 blue Tentacle creature tokens.
{8}: Counter target spell unless its controller pays {8}.
{8}: Draw eight cards.

Invigorate X, where X is the number of creatures you control. (Choose a creature with the least power among creatures you control and put X +1/+1 counters on it.)

At the beginning of each end step, if a creature an opponent controlled died this turn, return a creature card from your graveyard to the battlefield.

Attacking creatures get -3/-0 until end of turn.

Copse Tyrant can't be blocked by creatures with power 2 or less.
Spells and abilities your opponents control can't cause cards to leave your graveyard.
Whenever Copse Tyrant deals combat damage to a player, return up to two target permanent cards from your graveyard to your hand.

Flying, menace
Whenever another creature you control deals combat damage to a player, sacrifice it.
If you would draw a card, you may instead return a creature card from your graveyard to your hand.

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
Scry 2, then draw two cards. If you're in a renaissance, instead scry 2, then draw three cards.

Menace
At the beginning of your end step, He of All Hallow's Eve deals damage equal to its power to you unless you're horrific. (You're horrific as long as you've sacrificed a permanent or discarded a card this turn.)

Flash
Advance {3}{W} (Cast this for {3}{W} to advance it as it enters. {3}{W}: Advance this as a sorcery.)
Whenever Steelwoven Soldier advances, it gets +2/+2 until end of turn.

As long as you control exactly two creatures, those creatures get +2/+1 and have lifelink.

Flying
When Heartless Host enters, arm target creature. (Create a colorless Equipment artifact token with “Equipped creature gets +1/+0” and equip {2}, then attach it to that creature.)

Whenever a nonbasic nontoken land enters under an opponent's control, create a tapped colorless land token named Fading Rift with “{T}, Sacrifice this land: Add one mana of any color.”

Kahroba Pureblood has trample as long as it has a counter on it.

Exile target attacking or blocking creature with power 4 or less.

Whenever Pilgrim of Xifang's Climb blocks a creature, that creature doesn't untap during its controller's next untap step.