msem-instigator

Flying
{1}{U}: Reveal the top card of your library. Moonwing Watcher's base power becomes equal to that card's mana value.
Prophecy {U} (Once each turn, you may exile a card with prophecy as you reveal it. When you do, you may cast it for its prophecy cost as long as it's exiled.)

At the beginning of your upkeep, you may put a reinforcement counter on Moranai Paragon.
Whenever Moranai Paragon attacks, you may put a creature card with mana value equal to the number of reinforcement counters on Moranai Paragon from your hand onto the battlefield.

Deathtouch

{4}{G}: Monstrosity 2. (If this creature isn't monstrous, put two +1/+1 counters on it and it becomes monstrous.)
When Mountain Bighorn becomes monstrous, you may have it fight target creature you don't control.

Kicker {2}{R} (You may pay an additional {2}{R} as you cast this spell.)
Haste (This creature can attack and {T} as soon as it comes under your control.)
If Mountain Victor was kicked, it enters with two +1/+1 counters on it.

When Mountain-Western Inventor enters, you may return target artifact card from your graveyard to your hand.
{1}, Sacrifice an artifact: Target creature can't block or be blocked this turn.

Double strike

Sacrifice another colorless creature: Put a +1/+1 counter on target creature.

Haste
Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)

When Mul Daya Elder enters, search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Whenever a land you control enters, put a +1/+1 counter on Mul Daya Elder.

Multipurpose Mannequin gets +1/+1 for each permanent attached to it.

{T}: Add {C}. Spend this mana only to cast a creature spell with a creature type no creature you control has.

Whenever a player casts a spell, that player exiles the top card of each library face down.
Each player may look at and play cards they exiled with Mystic of Many Winds.

Stampede — Whenever Nacatl Skirmisher and a creature with greater power attack, creatures you control get +1/+0 until end of turn.
{R}, Sacrifice Nacatl Skirmisher: Destroy target artifact.

{T}, Discard a card: Draw a card.

When Naive Apprentice enters, each player creates a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
As long as an opponent controls an artifact, Naive Apprentice gets +2/+0.

{2}{U}, Sacrifice Nameless Drifter: Draw a card for each creature that left the battlefield this turn.

Vigilance (Attacking doesn't cause this creature to tap.)

Flying
{2}{U}, {T}: Target creature gets +1/+1 and gains flying until end of turn. Activate only as a sorcery.

Deathtouch
When Necrodromos enters, put a +1/+1 counter on target creature.

When this creature enters, draw a card.

Deathtouch
When Nel Toth Shaman enters, mill two cards.

Whenever Neo-Soul Attendant or another enchantment you control enters, you gain 1 life.

When Nephilim Wisdomancer enters, mill three cards. Then you may pay {W}{B}. If you do, return a nonland card from your graveyard to your hand.

Whenever Netsight Trickster deals combat damage to an opponent, create a Function token with “Draw a card. Then discard a card unless you pay {2}.” (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)