msem-instigator

First strike
Whenever a nontoken creature you control leaves the battlefield, you may pay {W}. If you do, create a 1/1 colorless Spirit creature token.

Preacher of the Yenzu gets +2/+0 and has flying as long as you control a legendary creature.

Vanishing 5 (This permanent enters with five time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
Players play with the top card of their libraries revealed.
Whenever a time counter is removed from Precarious Ledgers, you may have target player mill a card.

Look at target opponent's hand. You may exile a noncreature, nonland card from it. For as long as that card remains exiled, its owner may cast it. A spell cast this way costs {2} more to cast.
Draw a card.

(Activate each submodule once as a sorcery. When this enters, activate one submodule for free.)
Flash
{2}{W}: Prioritize
Put two +1/+1 counters on target tapped creature.
{2}{U}: Precipitate
Look at the top six cards of your library. Exile one face down, then shuffle. For as long as that card is exiled, you may cast it if it's an instant or has flash.
{1}{W}{U}: Process
Precognition Module gains “Whenever you cast another spell with flash or an instant, surveil 2.”

When Precursor Custodians enters, exile up to one target creature. As long as that card remains exiled, its owner may cast it. A spell cast this way costs {2} more to cast.

{1}, {T}: Add one mana of any color.
Crew 1 (Tap any number of creatures you control with total power 1 or greater: This Vehicle becomes an artifact creature until end of turn.)

As Precursor Gate leaves the battlefield, you may exile it. When you do, destroy target nonland permanent.
{5}, {T}, Sacrifice Precursor Gate: Draw a card.

Whenever Precursor Omniprocessor attacks, you may sacrifice an artifact or creature. If you do, put a +1/+1 counter on Precursor Omniprocessor and it gains menace 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.)

Converge — Precursor Sentinel enters with a +1/+1 counter on it for each color of mana spent to cast it.
Remove a +1/+1 counter from Precursor Sentinel: It deals 1 damage to any target.

Equipped creature gets +1/+1 and has menace.
Equip {R}

Creatures can't attack you unless their controller pays {2} for each of those creatures.
Mirage {1}{U} (You may cast this spell as though it had flash for its mirage cost. If you do, sacrifice it at the beginning of the next cleanup step.)

Target creature you control deals damage equal to its power to another target creature. You gain 3 life.

Predatory Abomination has deathtouch and lifelink as long as you control another Horror.

Choose a creature. When it dies this turn, distribute two +1/+1 counters among any number of creatures you control.

Flash
When Predatory Psion enters, switch target creature's power and toughness until end of turn.

Enchant creature
You choose whether enchanted creature attacks each combat rather than its controller (after its controller chooses which of their other creatures attack. That player still chooses the player or planeswalker it attacks.)

Nontoken creatures get -2/-2 until end of turn.
Fuse (You may cast one or both halves of this card from your hand.)

If one or more +1/+1 counters or quest counters would be put on a permanent you control, that many plus one of those counters are put on it instead.

Scry 3.
Catalyze. (The next spell you cast this turn costs {1} less to cast.)

Creatures you control get +0/+2 until end of turn. Untap those creatures.

Put a +1/+1 counter on target creature.
Draw a card.

Target creature you control gains double strike until end of turn. That creature also gains trample until end of turn if you control a creature with power 4 or greater.

(Add a quest counter as this enters. Sacrifice after 3.)
Whenever a creature you control enters, add a quest counter.
Create a Treasure token.
Creatures you control get +2/+2 and gain trample and haste until end of turn.
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Creatures you control gain deathtouch until end of turn and must be blocked this turn if able.