msem-instigator

When Powercell Cultivator enters, create a tapped colorless Powercell artifact token with “{T}: Add {C}.”
Artifacts you control have “{T}: Add one mana of any color.”

Whenever Practical Battlemage attacks, catalyze. (The next spell you cast this turn costs {1} less to cast.)

When Practiced Sorcerer enters, return target noncreature, nonland card from your graveyard to your hand.

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.

{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.)

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

Flash
When Pride of Thorns enters, it gets +3/+3 until end of turn.

As an additional cost to cast this spell, pay {2} or reveal an instant or sorcery card from your hand.

Vigilance
Whenever another creature you control enters, scry 1.
{T}: Reveal the top card of your library. If it's a creature card, put it into your hand. Otherwise, you may put it into your graveyard.

{2}, {T}, Sacrifice a creature: Each opponent loses 2 life. You gain life equal to the life lost this way.

Prowess, haste
Whenever you cast an instant or sorcery spell, you may shuffle the cards in your hand into your library, then draw that many cards.

Each player can't untap more than one nonbasic land during their untap step.

When Primordial Progenitor dies, create two 1/1 red Elemental creature tokens.

{2}: Add one mana of any color.

When Prismatic Basilisk enters, you may search your library for a permanent card with mana value 1 or less, reveal it, put it into your hand, then shuffle.
{2/W}{2/U}{2/B}{2/R}{2/G}: Prismatic Basilisk gets +5/+5 and gains flying until end of turn.

Flying
{3}: Prismscale Dragon gets +1/+1 until end of turn for each color of mana spent to activate this ability.

Defender
Whenever you cast an enchantment, instant, or sorcery spell, scry 1 if it's the first time this ability has resolved this turn. If it's the second time, Prismscale Piranhas can attack this turn as though it didn't have defender. If it's the third time, whenever Prismscale Piranhas deals combat damage to a player this turn, draw a card.

Double strike
Concord — Pristine Duelist gets +2/+1 as long as there are four or more card types among permanents you control.

Profane Emissary gets +2/+2 and has lifelink as long as you control a Demon.
If you would draw a card, you may instead search your library for a Demon card, reveal it, put it into your hand, then shuffle. You lose life equal to that card's mana value.

{1}, {T}: Copy target activated or triggered ability you control. You may choose new targets for the copy.
{3}{U}, {T}: Copy target spell you control. You may choose new targets for the copy. (A copy of a permanent spell becomes a token.)

Whenever another nontoken creature you control enters, if it has a different name than each other creature you control and card in your graveyard, you may create a token that's a copy of it.

Erratic (When this creature dies, reveal the top four cards of your library. Put a creature card that costs less than this revealed this way onto the battlefield and the rest on the bottom of your library in any order.)
Morph {1}{G} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

When Project Head enters, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
{2}{U}, Exile Project Head: Shuffle your hand and graveyard into your library, then draw seven cards. Activate only if you control seven or more artifacts.

As long as another creature you control is attacking, Prolific Thief can't be blocked.
Whenever Prolific Thief deals combat damage to a player, draw a card, then discard a card.

Distorted (This creature can be blocked by tapped creatures but not untapped creatures.)