msem-instigator

Put a -1/-1 counter on target creature. Target creature you control fights that creature.

Whenever Polgek Songcrafter attacks, other attacking creatures you control get +1/+0 until end of turn. If you control five or more attacking creatures, choose up to one target creature the defending player controls. That creature can't block this turn.

This spell can't be countered.
Polis's Demise deals 5 damage to each creature. Destroy all artifacts.

Changeling (This card is every creature type.)
{T}: Add {C}.

Whenever you cast a spell that doesn't share a color with Pond Tenders, you may put target card from your graveyard on the bottom of your library.

({T}: Add {W} or {U}.)
Pool of Light enters tapped unless you control a basic Plains or a basic Island.

As Port Town enters, you may reveal a Plains or Island card from your hand. If you don't, Port Town enters tapped.
{T}: Add {W} or {U}.

{1}, {T}: Return target creature you control and each Aura attached to it to their owners' hands. Activate only as a sorcery.

[+1]: Create a 1/1 green Merfolk creature token.
[0]: Target artifact or creature loses all abilities and becomes a green Seal creature with base power and toughness 3/3.
[–6]: Up to five target noncreature permanents lose all abilities and become green Merfolk creatures with base power and toughness 1/1.

When Possibility Engine enters, exile the top two cards of your library.
Wanderlust — During each of your turns, if you control four or more differently named lands, you may play a card exiled with Possibility Engine.

Whenever a player cycles a card, Possibility Grinder gets +2/+2 until end of turn.

At the beginning of your upkeep, exile the top card of each of your libraries.
Put X cards exiled with Possibility Matrix on the bottom of their owner's library: You may cast a nonland card exiled with Possibility Matrix with mana value X or less without paying its mana cost.

When Possibility Scope enters, search your library for a land card, exile it, then shuffle.
{T}: Target land you control becomes a copy of a land card exiled with Possibility Scope until end of turn.

This spell costs {2} less to cast if an opponent controls a creature with a bounty counter on it.
Postmark Bullet deals 3 damage to any target.

At the beginning of each upkeep, if it's an extra turn, end the turn.
If a player would search a library, that player searches the top four cards of that library instead.

Vigilance, trample
{5}{R}{G}: Monstrosity 4. (If this creature isn't monstrous, put four +1/+1 counters on it and it becomes monstrous.)

This spell costs {1} less to cast for each artifact you control.
Choose two —
• Creatures without flying can't block this turn.
• Two target creatures get +2/+0 until end of turn.
• Power Drive deals 3 damage to any target.

Whenever a creature you control deals combat damage to a player this turn, add that much {R}. Until end of turn, you don't lose this mana as steps and phases end.

{T}: Add one mana of any color. Spend this mana only to cast a multicolored spell.

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.”

When Powercell Engineer enters, create a tapped colorless Powercell artifact token with “{T}: Add {C}.”

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

({T}: Add {R} or {G}.)
Practice Range enters tapped unless you control two or more basic lands.

As Prairie Monastery enters, you may tap an untapped creature you control. If you don't, Prairie Monastery enters tapped.
{T}: Add {G} or {W}.

({T}: Add {R} or {W}.)
As Prayer Hall enters, you may pay {1}. If you don't, Prayer Hall enters tapped.