msem-instigator

{2}{G}: Cryptozoologist voyages. (If it isn't blocking or targeted by another spell or ability, it phases out.)
Whenever Cryptozoologist phases in, you may put a creature card from your hand onto the battlefield until Cryptozoologist leaves the battlefield. (It returns to your hand if it's still on the battlefield.)

Cadence (Whenever you cast a spell, if its mana value is greater than this creature's power, put a +1/+1 counter on this creature.)
United Patrol can block an additional creature each combat.

Put a +1/+1 counter on target creature you control. Prevent all damage that would be dealt to that creature this turn.

Whenever Slaffield Workgate or another enchantment you control enters, create a 0/2 white Ox creature token.
{3}{W}: Return another target enchantment you control to its owner's hand.

{T}: Add {G}.

Haste
When Gilded Gearhulk enters, you may destroy target noncreature, nonland permanent.

Creatures you control get +1/+1.
{5}{W}: Create a 1/1 white Soldier creature token. Activate only as a sorcery.

When Harbinger of Growth enters, create a 1/1 green Saproling creature token.
{1}{G}, Sacrifice Harbinger of Growth: Populate. (Create a token that's a copy of a creature token you control.)

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Artifacts and creatures your opponents control enter tapped.

Assault {2}{R} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
When Monstrous Hila assaults, it deals 3 damage to any target.

When Telarine Ascendant enters, create a 1/1 Scout creature token that's all colors.
Creature tokens you control have vigilance.

Inspired — Whenever Bearer of Vile Incense becomes untapped, create a 0/1 black Cultist creature token with “{1}{B}{B}, Sacrifice three Cultists: Create a 5/5 black Demon creature token.”

Flying
Starbane Elemental's power and toughness are each equal to the number of creatures with flying you control.
When Starbane Elemental enters, destroy all creatures without flying.

At the beginning of each player's end step, if they aren't horrific, Bloody Valentine deals 2 damage to that player. (You're horrific as long as you've sacrificed a permanent or discarded a card this turn.)

Tap up to two target creatures. They don't untap during their controller's next untap step.
Reprise {3}{U} (As you cast an instant or sorcery spell, you may exile one card with reprise from your graveyard and pay its reprise cost. If you do, add its effects to that spell.)

Trample
Whenever Unstoppable Zealot deals damage to a player or noncreature permanent, you may put a land card from your hand or graveyard onto the battlefield.

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn.
Agonize (You may cast this card from your graveyard by putting a -1/-1 counter on a creature you control in addition to paying its other costs. Then exile this card.)

Haste
Whenever you cast a noncreature spell, put a +1/+1 counter on Rahstahde's Firefist. It gains menace until end of turn.

Whenever a creature an opponent controls deals damage to you, monstrosity 2. (If this creature isn't monstrous, put two +1/+1 counters on it and it becomes monstrous.)
Frigid Behemoth can't attack unless it's monstrous.

Flash
Flying
Whenever this creature enters or you cast a spell during an opponent's turn, you may exile target non-Cat permanent you control, then return that permanent to the battlefield tapped under its owner's control.

Target creature gets -2/-2 until end of turn. When that creature dies this turn, create a tapped 2/2 black Zombie creature token.

Enchant creature
When Sythian Scripture enters, put two +1/+1 counters on enchanted creature.
Enchanted creature gets +1/+1 and has indestructible and lifelink if you controlled a white legendary creature or planeswalker as you cast Sythian Scripture.

Creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, Bellowing Thoctar gets +2/+2 until end of turn.

Flying
Whenever Blizzard Dragon attacks, tap an artifact, a creature, and a land defending player controls. They don't untap during their controller's next untap step.
At the beginning of each opponent's upkeep, that player sacrifices a tapped permanent.