msem-instigator

{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}

{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.”)

{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.

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

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

You may play Grisly Ruins from your graveyard as long as seven or more cards are in your graveyard.
Grisly Ruins enters tapped.
{T}: Add {B} or {G}.
Cycling {1}{B}{G} ({1}{B}{G}, Discard this card: Draw a card.)

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}

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

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

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

Guang Shrine enters tapped.
{T}: Add {G} or {W}.
{G/W}, {T}, Sacrifice Guang Shrine: Put a +1/+1 counter on target creature you control. Activate only as a sorcery.

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.

Guidestone enters tapped.
{T}: Add {C}.
{2}, Sacrifice Guidestone: Draw a card.

When Gulch Custodian enters, return an artifact you control to its owner's hand.

{2}, Sacrifice a creature or artifact: Hadak's Guardian deals 2 damage to any target.

Attacking creatures you control get +1/+0.

Equipped creature gets +3/+2.
Equip {4}
Hail of Blades's equip ability costs {4} less to activate if it targets an equipped creature.

Puzzlebox (Begin the game with this and another card you own from outside the game in the command zone, locked. That card is face down until you unlock this.)
{1}, Sacrifice two Clues: Unlock Hall of Lost Histories and put the revealed card into your hand.

{T}: Add {C}.
{3}, {T}, Sacrifice Hall of Random Access Memories: Return target artifact, instant, or sorcery card from your graveyard to your hand.

Enchant player
Creature tokens enchanted player controls get +1/+1.

{T}: Add {C}. You gain 1 life.

{T}: Add {C}.
{T}: Add one mana of any color. Activate only if you have a counter.

As long as your deck contains only black and colorless cards, your minimum deck size is reduced by eight.

Indestructible
Whenever Hannaru the Conqueror attacks, put a +1/+1 counter on each creature you control.