msem-instigator

Vigilance
Death knell — Tap up to two creatures you don't control. (As a creature you control dies, trigger one death knell of that creature or another permanent you control.)

Defender (This creature can't attack.)
Hexproof (This creature can't be the target of spells or abilities your opponents control.)

When Gateway Statues enters, put a +1/+1 counter on target creature you control.
{T}: Add one mana of any color.

(Add a quest counter as this enters. Sacrifice after 3.)
Whenever a creature dies, add a quest counter.
Target player loses 1 life and you gain 1 life.
Put target creature card from a graveyard onto the battlefield under your control.
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Gathering Beacon enters tapped.
{T}: Add {G}.
{2}, {T}, Sacrifice Gathering Beacon: Choose a creature or planeswalker type, then reveal the top five cards of your library. You may put a card of the chosen type into your hand, then put the rest on the bottom in any order.

Whenever one or more +1/+1 counters are put on a creature you control, you may search your library for a creature card, reveal it, put it into your hand, then shuffle.

When Gau Ding Soulhoard dies, create X 1/1 colorless Spirit creature tokens, where X is its power.
Scavenge {4}{B} ({4}{B}, Exile this card from your graveyard: Put a number of +1/+1 counters equal to this card's power on target creature. Scavenge only as a sorcery.)

At the beginning of your upkeep, mill two cards.
{1}{B}{B}: Until end of turn, Gaunt Abnormality becomes a copy of target creature card in your graveyard, except it's 3/3.

[+1]: Creatures you control get +0/+1 until your next upkeep. Untap those creatures.
[–2]: Put target tapped creature into its owner's library third from the top.
[–7]: You get an emblem with “Whenever a nonland permanent you control is put into a graveyard from the battlefield, each opponent sacrifices a nonland permanent.”

First strike
When Gavis's Dragoons enters, exile another target creature until Gavis's Dragoons leaves the battlefield.
Spells with the same name as the exiled card can't be cast (as long as this creature is on the battlefield).

Enchant opponent
Enchanted player plays with the top card of their library revealed.
Whenever enchanted player casts a spell, you may have them mill a card.

Flying
{1}, Sacrifice Gearcraft Observer: Look at target player's hand. Draw a card.

{1}{U}{R}, {T}: Create a token that's a copy of another target creature, except it's an artifact in addition to its other types and has “Whenever this creature is dealt damage, destroy it.”

When Gemcrusher Turtle enters, choose one —
• Destroy target artifact.
• Gemcrusher Turtle fights up to one target creature.

When you cast a creature spell, sacrifice Gemini Cast. If you do, create a token that's a copy of that spell, except the token isn't legendary.

When Gemplate Golem enters or dies, put a +1/+1 counter on target creature you control.

Flying
When Gemscale Drake enters, create a Treasure token.
Whenever Gemscale Drake deals combat damage to a player, scry 1. If you control three or more artifacts, draw a card instead.

Whenever you cast a spell with mana value 5 or greater, create an X/1 red Mutant creature token with trample and haste, where X is that spell's mana value. Exile that token at the beginning of the next end step.

When GenTech Architect enters, create a Function token with “Put two +1/+1 counters on a creature you control.” (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)

When GenTech Assistants enters, create an X/X green Mutant creature token.

Once during each of your turns, when you sacrifice a permanent, you may have target opponent lose 3 life unless they sacrifice a nonland permanent or discard a card.

GenTech Labs enters tapped.
{T}: Add {G} or {U}.
{G}{U}, {T}: Create a Function token with “This spell costs {1} less to cast if its mana value is 5 or greater.” Activate only if you have four or more cards in hand. (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)

When Gendran Hostess enters, you may search your library for a basic land card, reveal it, put it into your hand, then shuffle.

{T}: Add {C}.
{T}: Choose a color from among permanents you control. Add one mana of that color.

Motivate 3 (When this creature enters, you may motivate target creature with less power than this by putting three +1/+1 counters on it.)
When General Merthilios motivates a creature, that creature gains first strike, trample, and haste until end of turn.