msem-instigator

Destroy target creature or planeswalker. Create a Treasure token.

{T}, Sacrifice Grim Courtyard: Search your library for a Swamp or Forest card and put it onto the battlefield tapped, then shuffle.

When Grim Festivities enters or at beginning of your upkeep, you may return a creature card from your graveyard to the battlefield under your control. If you do, each opponent may return a creature card from their graveyard to their hand.

Whenever another Citizen you control dies, you gain 2 life.
{2}{B}, Exile a Citizen card from your graveyard: Each opponent loses 2 life.

{B}, {T}, Exile two cards from your graveyard: Create a 1/1 white Spirit creature token with flying.

When Grim Procession enters, create two 2/2 black Zombie creature tokens.
{2}{B}: Surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)

Target player sacrifices a creature. Create a tapped 2/2 black Zombie creature token.

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

{T}, Pay 1 life: Add {B} or {R}.
{1}, {T}, Sacrifice Grim Slums: Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Whenever another nonland creature you control dies, return it to the battlefield tapped with a sapling counter on it. It becomes an Animus land named Bitter Hazel, loses all other card types, and gains “{T}: Add {G}” and “Pay this card's mana cost: This land becomes a creature until end of turn. It's still a land.”

{2}, {T}: Create a Treasure token. (It's an artifact with “{T}, Sacrifice this permanent: Add one mana of any color.”)
{W}{U}{B}{R}{G}, {T}, Sacrifice Grim's Warchest: Exile target creature.

Flash
Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
When Grim enters, if you sacrificed a permanent this turn, exile target tapped creature.

Enchant creature
Enchanted creature has experience. (Whenever it attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)

Sacrifice another creature: Grindlesnap gets +3/+2 and gains trample until end of turn if that creature was a Crocodile. Otherwise, it gets +1/+1 until end of turn.
Whenever Grindlesnap is dealt combat damage, create a 3/2 green Crocodile creature token with trample.

Rapport — Whenever Grinning Fox and at least one other creature you control become tapped, tap another target creature. That creature doesn't untap during its controller's next untap step.

Deception {2}{B} ({2}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Grinning Torturer deals combat damage to a player, torment that player. (They lose 3 life unless they discard a card or sacrifice a nonland permanent.)

Enchant creature
When Grip of Paranoia enters, enchanted creature's controller loses 2 life.
Enchanted creature gets -3/-1 and can't block.

Enchant creature
Enchanted creature gets +1/-1.
When Grip of the Deadwood is put into a graveyard from the battlefield, return it to its owner's hand.

Put target creature on top of its owner's library.

Each player sacrifices a creature, then you gain 2 life for each creature that died this turn.

Enchant opponent
When Grisly Hunger enters, enchanted player's life total becomes 10.
At the beginning of enchanted player's end step, they sacrifice a creature. If they do, they lose life equal to that creature's power.

Grisly Marsh enters tapped unless another player controls a land that could produce {B} or {G}.
{T}: Add {B} or {G}.

Trample
At the beginning of each combat, you may have Grisly Offering deal 3 damage to target creature you control. If you do, Grisly Offering gets +3/+0 until end of turn.

When Grisly Reaper enters, you may exile a creature card from your graveyard. When you do, create a 1/1 black Skeleton creature token.

Sacrifice another creature: Grisly Rougarou deals damage equal to the sacrificed creature's power to any target.