msem-instigator

As an additional cost to cast this spell, pay {3} or discard a card.
Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)

Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)
Whenever Mukal Warleader attacks, the next Construct spell you cast this turn costs {1} less to cast.

Whenever Murkriver Trawler attacks, until end of turn, target Rogue gains “Whenever this creature deals combat damage to a player, draw a card.”

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

When Mythos Scribe enters, you may return target storied card from your graveyard to your hand. (Enchantments and legendary permanents are storied.)

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.

When Naga Cultivator enters, you may put a land card from your hand onto the battlefield.

When Naiad of the Glen enters, 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.”)
Naiad of the Glen has trample as long as it has a +1/+1 counter on it.

Nameless Throng can't block.
{1}{B}, Exile an artifact or enchantment card from your graveyard: Return Nameless Throng from your graveyard to the battlefield.

Trial 2 (As you cast this spell, an opponent of your choice may pay 2 life. If they don't, they fail the trial.)
When Nascent Adversary enters, if the trial was failed, it gains haste and first strike until end of turn.

Vigilance, deathtouch
Prevent all damage that would be dealt to Nataila, Raven's Repented while it's attacking or blocking alone.

Neckbreaker Viking gets +1/+0 and has menace as long as it's embattled. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

{1}{B}, Sacrifice another creature: Put a +1/+1 counter on Nemesis Eidolon. Draw a card. Activate only as a sorcery.

When Neo-Alchemist enters, you may reappropriate. If you do, distribute two +1/+1 counters among creatures you control. Otherwise, put a +1/+1 counter on up to one target creature you control. (To reappropriate, exile exactly two cards from your hand and/or graveyard.)

Whenever you gain life, put a +1/+1 counter on Neo-Soul Envoy.

When Neo-Soul Naturalist enters, exile up to one target artifact or enchantment. Its controller conjures a card named Data-Point into their hand. (It's a sorcery that costs {2} with “Draw a card.”)

Neo-Soul Nihilist has lifelink as long as it's attacking.
When Neo-Soul Nihilist is put into your graveyard from anywhere, you may pay 2 life. If you do, conjure a card named Data-Point into your hand. (It's a sorcery that costs {2} with “Draw a card.”)

Whenever another enchantment you control enters, put a +1/+1 counter on Neo-Soul Prophet and conjure a card named Data-Point into your hand. (It's a sorcery that costs {2} with “Draw a card.”)

Whenever you discard a card, tap up to one target creature.

Deathtouch
When Neophyte of the Old Gods enters, rediscover a sorcery card. (Look at the top card of your library. You may reveal it and put it into your hand if it's a sorcery card. Otherwise, put it back or into your graveyard.)

Flash
When Nephalia Inquisitors enters, draw a card for each creature that died this turn.

Chronicle (As this enters and after your draw step, add a lore counter. Stop after III.)
[Lore I-II] Each player loses 1 life.
[Lore III] Create a 1/1 black Harpy creature token with flying.

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.)

Harmony — You gain 2 life.
When New Alores Fiddler enters, harmonize. (Trigger up to one harmony of one permanent you control.)