msem-instigator

This spell costs {1} less to cast for each permanent you control that's a Dragon or a Hound.
Flying, haste
Whenever Gold Retriever attacks, abound. (You may cast a nonland card that costs less than this from your hand without paying its mana cost.)

When Goldhill Guardian enters, choose a creature type.
Goldhill Guardian has protection from creatures of the chosen type. (It can't be blocked, targeted or dealt damage by creatures of the chosen type.)

Spells you cast with mana value 4 or greater cost {1} less to cast.

When Goriana Earthshaker enters, you may untap target land you control. It becomes a 3/3 Elemental creature with haste until end of turn. It's still a land.

Motivate 2 (When this creature enters, you may motivate target creature with less power than this by putting two +1/+1 counters on it.)
Each creature you control with a +1/+1 counter on it has trample.

Motivate 1 (When this creature enters, you may motivate target creature with less power than this by putting a +1/+1 counter on it.)
When Goriana Tactician enters, you may tap target creature.

Flash (You may cast this spell any time you could cast an instant.)
When Gorillas in the Mist enters, prevent all combat damage that other creatures would deal this turn.

Flying, vigilance
When you unveil Graced Theurge, draw a card.

Vigilance
Whenever the final chapter ability of a Saga you control resolves, you may return a non-Saga card at random from your graveyard to your hand.

Whenever Gravelocked Seeker blocks, return target creature card from your graveyard to the battlefield blocking a creature that's attacking you (even if that block would be illegal).

Flying, trample
When Greedstoker Demon enters, you lose X life and create X Treasure tokens, where X is your devotion to black. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)
You can't sacrifice more than one Treasure each turn.

When Greedy Insects enters, exile up to one target artifact or enchantment until Greedy Insects leaves the battlefield.

Trample

Menace
Disgraced 1 (This enters with a -1/-1 counter. Whenever it deals combat damage to a player, remove all -1/-1 counters from it.)

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

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.”

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.

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.

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

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}

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

Other creatures you control that are Knights or have Adventures get +1/+1.

When Guardian of Lost Truths enters, if a library has twenty or fewer cards left in it, draw two cards. Otherwise, target player mills five cards.

Menace
Death knell — Put a +1/+1 counter on Guiltless Wraith. (As a creature you control dies, trigger one death knell of that creature or another permanent you control.)

Reach, trample
{1}{G}: You may remove a counter from a creature you control. If you do, tap that creature and it gains indestructible until end of turn.