msem-instigator

Distorted (This creature can be blocked by tapped creatures but not untapped creatures.)
When Arbiter of Shal'Iv enters, adjudicate. (Create a white enchantment Aura token with enchant creature and “Sacrifice this token: Untap enchanted creature” attached to target creature.)

Choose one or both—
• Target creature has base toughness 1 until end of turn.
• Remove all but one loyalty counter from target planeswalker.

Enchant creature
When Karametra's Touch enters, you gain 2 life.
Enchanted creature gets +2/+2.
When enchanted creature dies, return Karametra's Touch to its owner's hand.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Create two 1/1 colorless Construct Actor creature tokens.
II, III — Creatures you control gain flying until end of turn. Whenever one or more of them deals combat damage to a player this turn, draw a card.
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Serene Chapel enters tapped unless you control a basic Plains.
{T}: Add {W}.
{1}{W}{W}: Until end of turn, Serene Chapel becomes a 2/1 white Spirit Cleric creature with flying and “Whenever this creature attacks, you may exile target card from a graveyard.” It's still a land.

Flash
Flying
When P05 Suppressor enters, create a Function token with “Tap target creature. Put a stun counter on it.” (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)

Search your library for two basic land cards and put them onto the battlefield tapped. Then they become 0/1 green Plant creatures with “This creature can't block” in addition to their other colors, types, and abilities.

When this creature enters or leaves the battlefield, create a tapped 2/2 black Zombie creature token.

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Whenever Boghex Witch deals combat damage to a cursed player, that player loses the game.
{2}{B}: Look at the top five cards of your library. You may reveal a Curse card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Whenever Shifty Fink attacks, if you have more cards in hand than defending player, it gets +2/+1 until end of turn.

{T}: Add {C}{C}. Spend this mana only to cast spells with mana value 5 or greater.

Flash
When Agent of Equilibrium enters, destroy target creature or planeswalker an opponent controls that was dealt damage this turn.

For each creature you control, put a +1/+1 counter on it or create a Treasure token.

{1}{R}: Aravant Throatcutter and up to one other target Pirate or Rogue you control each get +1/+0 until end of turn.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
When Nizev Brawler enters, target creature can't block this turn.

As an additional cost to cast this spell, sacrifice a creature.
Enchant creature
Enchanted creature gets +4/+4, has flying, and is a Demon in addition to its other types.

When Yron Bay Sentinel enters, draw a card.

Target player discards two cards.
Kindle 2—{1}{B}{B} ({1}{B}{B}, Exile this card from your graveyard: Create two 1/1 colorless Elemental creature tokens. Kindle only as a sorcery.)

Destroy target planeswalker. Mummy's Grin deals 2 damage to that planeswalker's controller.

Rouse 1. Target permanent gains first strike until end of turn if it's a creature. (Put a +1/+1 counter on a permanent you control. If it isn't a creature, tap it and it becomes a 0/0 creature in addition to its other types.)

Enchant creature
When Sprawled Arming enters, put a +1/+1 counter on enchanted creature.
Enchanted creature has first strike.
{5}: Return Sprawled Arming to its owner's hand.

When Gloomy Waypoint enters, create a 1/1 black Scout creature token.
{T}: Add {W}, {B}, or {G}.

When Phantasmal Samaritan enters, you gain 4 life.

Flying
When Rapacious Regent enters, you may sacrifice another creature or artifact. If you do, Rapacious Regent deals 3 damage to any target.