msem-instigator

Ayala, Shrouded Shepherd can't attack or block unless your life total is greater than or equal to your starting life total.
Lifelink, indestructible
Whenever a creature attacks you or a planeswalker you control, you may pay {2}. If you do, create a 1/1 white Spirit creature token with lifelink blocking that creature.

Equipped creature gets +1/+0 and has wither. (It deals damage to creatures in the form of -1/-1 counters.)
Equip {2}

Deathtouch
Whenever you lose life, you may cast target black noncreature card in your graveyard this turn. If it would be put into a graveyard from anywhere this turn, exile it instead.
Whenever you gain life for the first time each turn, create a 1/1 black Actor creature token.

Menace
Sacrifice another artifact: Scrap Buggy becomes an artifact creature until end of turn.
Crew 2 (Tap any number of creatures you control with total power 2 or greater: This Vehicle becomes an artifact creature until end of turn.)

Foretell {1}{G}{G} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)
Choose one. If this spell was foretold, you may choose both instead —
• Create two tapped 1/1 white Peasant creature tokens.
• You gain 7 life.

Search your library for a card, put that card into your hand, then shuffle. If you control two or more creatures with -1/-1 counters on them, add {B}{B}{B}.
Agonize (You may cast this card from your graveyard by putting a -1/-1 counter on a creature you control in addition to paying its other costs. Then exile this card.)

Flying, lifelink
Whenever you gain life, you may have target creature get -X/-X until end of turn, where X is the amount of life you gained.

{T}: Add {G}.
Dominance — {T}: Add {G}{G}. Activate only if you control the creature with the greatest power or tied for the greatest power.

TT-20 Salvation gets +1/+1 for each other artifact you control.
As TT-20 Salvation enters, create a 1/1 colorless Servo artifact creature token.

Chosen one ({W}{U}{B}{R}{G}: Transform this permanent.)
[+2]: Exile the top two cards of your library. Until end of turn, you may play one card exiled with this permanent.
[+1]: Exile up to two cards from your hand, then draw that many cards.
[–3]: Menna, Servant to None deals 3 damage to up to one target player and up to one target creature or planeswalker.

You lose 1 life and exile the top card of your library. You may repeat this process any number of times. Then put up to two cards exiled this way into your hand.
Coalesce {5}{B}{B} (You may cast this from your graveyard for {5}{B}{B}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)
Black Hole Musings's power is equal to the number of cards in exile.

{U/B}{U/B}: Return Nherix, the Soulcage from your graveyard to the battlefield tapped.
{6}: Return target creature card with mana value 2 or less from your graveyard to the battlefield tapped.

When The Moon Rises enters, exile all opponent's graveyards.
At the beginning of your upkeep, each opponent loses 1 life.

First strike
Whenever Flintlock Pioneer deals damage, tap it. It doesn't untap during its controller's next untap step.

Equipped creature has “Whenever this creature attacks or blocks, choose a creature card in your graveyard. This creature gets +X/+Y until end of turn, where X is that card's power and Y is its toughness.”
Equip {2}

Put a number of +1/+1 counters on target creature you control equal to that creature's power.
Spell mastery — If there are two or more instant or sorcery cards in your graveyard, you may have that creature fight another target creature. (Each deals damage equal to its power to the other.)

You may have Ephemeral Qilin enter as a copy of a multicolored permanent you control.

This spell can't be countered.
Exile your library, then shuffle Revisionary Studies, your graveyard, and your hand into your library. Draw five cards.

Haste
When Kragnoss, Rebellion Commander enters, create a 1/1 red Goblin creature token.
Whenever a Goblin you control attacks, Kragnoss, Rebellion Commander deals 1 damage to target creature defending player controls.

Each planeswalker you control enters with an additional loyalty counter on it.
{T}: Add {C}.

Flying
Harmony — Until the end of your next turn, you may cast target instant or sorcery card from your graveyard. If that card would be put into your graveyard, exile it instead.
When Aven Acoustimancer enters, harmonize. (Trigger up to one harmony of one permanent you control.)

When Journey to the Zhedina enters, draw a card, then choose a creature card name.
Whenever a creature with the chosen name you control deals damage to a player, put a +1/+1 counter on it.

Search your library for up to four basic land cards, reveal them, put them into your hand, then shuffle. You may play an additional land this turn.

Legacy (You may play this side of this card only from your graveyard. Exile it if it would be put into a graveyard or not resolve.)
For each of up to two target creatures you control, put a +1/+1 counter on it, then you may have it deal damage equal to its power to any target.

Target creature gains double strike until end of turn. Mill a card.