msem-instigator

This spell costs {2} less to cast if a permanent you controlled left the battlefield this turn.
Target creature gets +3/+0 and gains trample until end of turn.

Flying, haste
Whenever Grieving Revenant attacks, it deals 1 damage to each other creature you control.

As an additional cost to cast this spell, tap an untapped artifact or creature you control.
Up to three target creatures can't block this turn.

As Grim Bastion enters, you may pay 2 life. If you don't, Grim Bastion enters tapped.
{T}, Sacrifice Grim Bastion: Search your library for a Swamp or Forest card, put it onto the battlefield, then shuffle.

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

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

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.”

Whenever Grin, Scourge of Goresand attacks, when you next cast an instant or sorcery spell with mana value 3 or less this turn, copy that spell. You may choose new targets for the copy.
Dash {2}{R} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)

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

Resolute — {T}: Grizzled Cutthroat deals 1 damage to any target. Activate only if Grizzled Cutthroat's power is greater than its base power.

Grizzled Den enters tapped.
{T}: Add {R} or {G}.
{3}{R}{G}: Until end of turn, Grizzled Den becomes a Bear creature with trample in addition to its other types.
Scavenge {4}{R}{G}

{4}{G}{G}: Monstrosity 4. (If this creature isn't monstrous, put four +1/+1 counters on it and it becomes monstrous.)
When Grizzly Matriarch becomes monstrous, destroy target noncreature permanent an opponent controls.

[+2]: Destroy up to one target noncreature permanent.
[0]: Grohl becomes a legendary green 6/6 Elk Giant creature with trample, hexproof, and haste until your next turn.
[–9]: For each permanent you control, create a token that's a copy of it.

Archive 6
Grohl's Study's power and toughness are each equal to the number of cards in the archived library.
Whenever Grohl's Study deals combat damage to a player, you may put a card from the archived library into your hand.

When Grotto Scarab enters, create two 1/1 green Insect creature tokens for each creature you controlled that died this turn.

Target creature gets +2/+2 until end of turn.
Landfall — If you had a land you control enter this turn, that creature gets +4/+4 until end of turn instead.

{T}: Add {C}.
{T}: Add one mana of any color. Activate only if two or more land cards are in your graveyard.

Create two 1/1 red Goblin creature tokens.

Target creature +3/+3 and gains trample until end of turn.
Leitmotif (If you cast this spell from your hand, exile it as it resolves. When you next cast a spell that shares a color with this card, you may cast this from exile without paying its mana cost.)

When Growth Paradigm enters, conjure a card named Data-Point into your hand. (It's a sorcery that costs {2} with “Draw a card.”)
Once each turn, when you cast a sorcery spell, you may create an X/X green Mutant creature token, where X is that spell's mana value.

Gruff Clutch enters with six +1/+1 counters on it.
{R}, Remove a +1/+1 counter from Gruff Clutch: It deals 1 damage to any target.

When Gruff Smith enters, you may destroy target artifact. If you do, that artifact's controller creates a colorless Equipment artifact token with “Equipped creature gets +1/+1” and equip {1}.
Recite {1}{R} (You may cast this creature from your graveyard for its recite cost. If you do, exile it when it enters or if it would leave the battlefield.)

{T}: Add {C}.
{T}, Exile two cards from your graveyard: Add {R} or {G}.

Flying
Whenever you cast a cryptic spell, Guardian of Mysteries becomes a 4/4 Sphinx creature in addition to its other types until end of turn. (Artifacts, enchantments, and modal spells are cryptic.)
{1}, {T}: Scry 2.