msem-instigator

Mill three cards, then you may return a creature or land card from your graveyard to your hand. (To mill three cards, put the top three cards of your library into your graveyard.)

Create a 2/2 red Dragon creature token with flying and haste.
Whenever a nontoken Dragon you control attacks, you may return Flynn's Wonder from your graveyard to your hand.

Gain control of target nonland permanent you don't control unless its controller has Bow or Burn deal X damage to them, where X is twice that permanent's mana value. If Bow or Burn was cast from a graveyard, repeat this process for each other nonland permanent they control.
Flashback {6}{R}{R}

Scry 2, then draw two cards.
You have no maximum hand size for the rest of the game.

{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Bleed {U/B} (You may cast this spell for its bleed cost if an opponent has lost life this turn.)
Target player mills eight cards.

Flying
Other creatures you control enter with an additional +1/+1 counter on them.
If a spell or ability an opponent controls causes you to discard Sigarda, Dawn of Mercy, put it onto the battlefield instead of putting it into your graveyard.

{1}, {T}: Add one mana of any color.
Crew 1 (Tap any number of creatures you control with total power 1 or greater: This Vehicle becomes an artifact creature until end of turn.)

At the beginning of your upkeep, you lose 1 life, then audition for black. (Create a 1/1 Construct Actor creature token, a Cleric Role giving 2/2 and lifelink, or a Warlock Role giving 2/1 and flying. Roles replace older ones.)

When Conquerer's Blade enters, create a 1/1 white Soldier creature token and attach Conquerer's Blade to it.
Equipped creature gets +1/+0 and has first strike.
Equip {3}

When Shaman of Burning Ashes enters, return target instant or sorcery card from your graveyard to your hand. When you do, each opponent loses X life, where X is that card's mana value.

Vigilance
Whenever you make first contact, put a +1/+1 counter on Volarian Sightseer. (You make first contact the first time each turn you cast a spell with a name not in your graveyard or control already.)

Destroy target creature. Create a tapped Treasure token.

When Silverhorn Battlemaster enters, put a +1/+1 counter on up to two target Warriors you control.
Whenever Silverhorn Battlemaster deals combat damage to a player, permutate. (You may remove a counter from a creature you control. If you do, put two +1/+1 counters on a different creature you control.)

When GenTech Architect enters, create a Function token with “Put two +1/+1 counters on a creature you control.” (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)

As an additional cost to cast this spell, discard two cards.
Put the bottom three cards of your library into your hand.

Rehison Soothemage has lifelink as long as you control another Elf.

Vigilance
Whenever one or more cards leave your graveyard, surveil 1.

Haste
When this creature enters, exile any number of noncreature, nonland cards from your graveyard. When you do, it gets +1/+0 for each card exiled this way until end of turn.
Arise 2R ({2}{R}, Exile this from your graveyard as a sorcery: Create a black token copy of it that's also a Zombie and can't block.)

Oshiruko Whisperwalker can't be blocked except by Rogues.
Whenever a creature is returned to its owner's hand, you may draw a card. If you do, discard a card.

Haste
Stampede — Whenever Fissure Bull and a creature with greater power attack, you may sacrifice a land. If you do, search your library for a basic land or Desert card, put that card onto the battlefield tapped, then shuffle.

{X}{W}{W}: Prevent the next X damage that would be dealt to target creature you control this turn. Whenever damage is prevented this way, you gain that much life.

Inspired — Whenever Pon's Apprentice becomes untapped, target creature you control has base power and toughness 5/5 until end of turn.

Enchant creature
When Philosophical Conundrum enters, scry 1.
Enchanted creature can't attack or block.