msem-instigator

Flying
Sacrifice Crystalcatcher: Counter target creature spell unless its controller pays {1}.

Flash
When Culi-Sae Mesmer enters, return all permanents attached to target permanent or player to their owners' hands.

Lifelink
Whenever you sacrifice a nonland permanent, you may pay {1}. If you do, you draw a card and you lose 1 life.

Hexproof (This creature can't be the target of spells or abilities your opponents control.)
As long as an opponent has ten or more cards in their graveyard, Cunning Infiltrator gets +3/+2 and can't be blocked.

Elemental, Demon, and Spirit spells you cast cost {1} less to cast.
Whenever you cast a Elemental, Demon, or Spirit spell, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Whenever you draw your second card each turn, put a +1/+1 counter on Current Surfer.
{R}, Discard your hand, Sacrifice Current Surfer: Draw X cards, where X is its power. At the beginning of the next end step, discard your hand.

When Customs Lookout enters, each player draws a card, then discards a card.
Whenever an opponent casts a spell with the same name as a card they own in exile or in their graveyard, you may scry 2.

Haste
Whenever a creature dealt combat damage by Cutthroat Carnie this turn dies, you may have Cutthroat Carnie fight target creature.

Whenever Cutthroat Spy deals combat damage to a player, you may draw a card.

When CySec Spectre enters, you may sacrifice a creature. If you do, target opponent loses 3 life and you gain 3 life.

Flash

When Cyone, Expedition Captain enters, create a 1/1 Scout creature token that's all colors, then choose flying, first strike, or lifelink. Creature tokens you control gain the chosen ability until end of turn.
Whenever Cyone attacks, aetherize it. (To aetherize, create a token that's a copy of it, then exile that token.)

Creature spells you cast cost {2} less to cast.
Whenever another nontoken creature you control enters, it becomes a colorless Vehicle artifact with crew 1. (Tap any number of creatures you control with total power 1 or greater: That Vehicle becomes an artifact creature until end of turn.)

Flying
Whenever DC-4 Cutie enters or attacks, choose target creature card with mana value 3 or less in your graveyard. You may cast it this turn.
Crew 2

Vigilance, reach
When DL-19 Reject enters, target creature you control gets +2/+2 until end of turn.

Mark (Whenever this creature attacks, mark target creature until end of turn.)
Whenever a marked creature an opponent controls dies, create a Food token. (It's an artifact with “{2}, {T}, Sacrifice this artifact: You gain 3 life.”)

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
{3}{G}: Da'Lang gets +2/+2 until end of turn. If you're in a renaissance, all creatures able to block Da'Lang this turn do so. Activate only once each turn.

Adorned — Daelish Archer has first strike as long as it's equipped and/or enchanted.

Flying (This creature can't be blocked except by creatures with flying or reach.)

Breach (Whenever this deals combat damage to a player, you may have it become an Aura Curse until your next turn. Attach it to that player.)
Whenever you cast a spell, Daemonspawn deals 1 damage to each cursed opponent.

Daggersworn Elite enters tapped.
Whenever Daggersworn Elite and at least two other creatures attack, you may pay {1}{B}. If you do, destroy target tapped creature.

Transcend (Activate as a sorcery to gain the next type and a +1/+1 counter.)
When Dai Gui enters, create a 1/1 green and blue Bird creature token with flying and “{T}: Add one mana of any color.”
{X}{X}{G}{U}: Demigod — You gain X life and you draw X cards. X can't be 0.
{X}{X}{G}{U}: God — Put up to X creature cards from your hand onto the battlefield.

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Frontiers Anew {G}
Sorcery — Adventure
Search your library for a basic land card, reveal it, put it into your hand, then shuffle. (Then exile this card. You may cast the creature later from exile.)

Other creatures you control get +1/+1 as long as you control four or more lands.
{G}, Sacrifice Daisy, the Heart of Chasmek: Creatures you control with base power 1 or less gain indestructible until end of turn.

Whenever a creature an opponent controls becomes blocked, put a -1/-1 counter on that creature.