msem-instigator

At the beginning of your upkeep, put a +1/+1 counter on Heyu, Immortal Hunter.
Whenever Heyu becomes the target of a spell or ability an opponent controls, counter it if Heyu has the greatest power among creatures on the battlefield.

Hibernation Den enters the battlefield tapped.
{T}: Add {W}.
{W}, {T}: You gain 1 life. Activate only as a sorcery and only if you control a white creature.

{T}: Add {G}.
Dominance — {T}: Add {G}{G}. Activate only if you control the creature with the greatest power or tied for the greatest power.

Flash
If a spell or ability an opponent controls would cause you to discard a creature card, you may put that card onto the battlefield instead.

Flying, lifelink

Alpha (You may have this creature enter the battlefield with a +1/+1 counter on it. If you do, it becomes alpha and can only attack alone.)
Lifelink

Target player creates two 1/1 white Spirit creature tokens with flying.
Fabled {3}{W}{W} (Then if you cast this for its fabled cost, put it onto the battlefield transformed attached to that player.)

Menace
Whenever Hui Zhou, the Dark Visage perseveres, you may destroy another target legendary creature. (A creature perseveres when it survives damage.)

Humble Fieldhand gets +1/+0 and has vigilance as long as you control an Equipment.

Menace
Other Zombies you control get +1/+1.
Whenever a Zombie you control dies, each opponent loses 1 life.

Scry 3, then reveal the top card of your library. If it's a creature card, Hunter's Instinct deals damage to target creature equal to the revealed card's power.
Ferocious — If the revealed card is a creature card with power 4 or greater, put it into your hand.

Hurtling Swine attacks each combat if able.

Enchant creature
When Hypnotic Halo enters the battlefield, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)
{2}{W}{W}, Sacrifice Hypnotic Halo: Exile enchanted creature.

Enchant artifact or creature
Enchanted permanent doesn't untap during its controller's untap step.

You may have Icefang Wurm assign its combat damage as though it weren't blocked.
{4}{G}{G}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)

{1}, {T}: Tap target artifact, creature, or land.

When Illustrious Lantern enters the battlefield, put a +1/+1 counter on target creature you control.
{4}, {T}: Put a +1/+1 counter on target creature you control.

Distribute three +1/+1 counters among any number of creatures you control.
Metamorph {1}{G} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up and cast it at any time for its metamorph cost.)

Enchant creature
Enchanted creature gets +3/+3 and has flying.

At the beginning of your upkeep, scry 2.
Reveal the top card of your library: If a creature card with flying was revealed this way, Imperial Chimera gains flying until end of turn. The same is true for first strike, double strike, deathtouch, haste, hexproof, indestructible, lifelink, menace, reach, trample, and vigilance.

Ferocious — At the beginning of each combat, if you control a creature with power 4 or greater, Impressible Cub gets +1/+1 until end of turn.

Enchant creature
When Inborn Instincts enters the battlefield, enchanted creature deals damage equal to its power to target creature an opponent controls.
Enchanted creature gets +6/+6.

Equipped creature gets +3/+2 and must be blocked by a creature that doesn't share a color with it if able.
Equip {4}

Deathtouch
Whenever Infected Null attacks, each player loses 1 life.

At the beginning of each end step, if a player lost 5 or more life this turn, create a 5/5 black Demon creature token with flying.