msem-instigator

Players can't get counters.
Counters can't be put on permanents.

Whenever a creature with flying attacks you, gain control of that creature at end of combat.

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.

Flying
When Namuzzar's Iterator enters, you may return an artifact or enchantment you control to its owner's hand.

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

Reach
Whenever you cast a spell with mana value 5 or greater, put two +1/+1 counters on Netcrawler.

Flying, lifelink
Whenever Nightfall Sphinx or another creature you control enters, each opponent loses 1 life and you gain 1 life.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever Nimble Elemental deals combat damage to a player, you may draw a card. If you do, discard a card.

Whenever an opponent discards a card, exile it. You may cast that card as long for as it remains exiled, and you may spend black mana as though it were mana of any color to cast that spell.

Flying
When Nizev Arbiter enters, judge another target creature you control. (Honor it by putting a +1/+1 counter on it or condemn it by sacrificing it to draw a card.)

When North Ward Settler enters, choose one —
• Create a 1/1 white Dwarf creature token.
• Put a +1/+1 counter on North Ward Settler.

Flying
Whenever Notorious Windraider attacks, other attacking Pirates and Rogues you control gain flying until end of turn.

Flying
When Novaheart Guardian enters, it deals 4 damage to any target.
Whenever a creature or planeswalker dies, put a +1/+1 counter on Novaheart Guardian.

Flying
Whenever Novean Sky Swallower blocks or becomes blocked by a creature with flying, destroy that creature, then put a +1/+1 counter on Novean Sky Swallower.

Flash
When Nurse Trainee enters, you may prevent the next 2 damage that would be dealt to another target creature this turn.

This spell costs {1} less to cast for each artifact and/or enchantment you control.
Trample
{1}, Sacrifice another cryptic permanent you control or exile a cryptic card from your graveyard: Put a +1/+1 counter on Observer of Aeons. (Artifacts, enchantments, and modal spells are cryptic.)

When Old Salt enters, forebode. (Create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.”)

Whenever you cast an instant or sorcery spell from your hand, you may cast target card with the same name as that spell from your graveyard. (You still pay its costs.)

Distorted (This creature can be blocked by tapped creatures but not untapped creatures.)
Spells you cast from zones other than your hand cost {3} less to cast.

Lifelink
Whenever a planeswalker dies, Onya's Chosen deals 3 damage to target creature or player.

When Oozing Yaoguai enters or a creature you control scavenges it, up to one target creature gets -3/-3 until end of turn and you gain 3 life.
Scavenge {3}{B}{G} ({3}{B}{G}, 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.)

Lifelink
Whenever Operative BABY attacks or you cast a black or red spell, create a 1/1 blue Elemental creature token with flying.

Menace
Whenever Operative GINGER attacks or you cast a blue or white spell, Operative GINGER deals 1 damage to any target.

Flash
Whenever Operative POSH attacks or you cast a green or red spell, exile up to one target nontoken permanent. Return that card to the battlefield under its owner's control at the beginning of the next end step.

Deathtouch
Whenever Operative SCARY attacks or you cast a green or white spell, you may draw a card. If you do, you lose 2 life.