msem-instigator

{1}, {T}: Copy target activated or triggered ability you control. You may choose new targets for the copy.
{3}{U}, {T}: Copy target spell you control. You may choose new targets for the copy. (A copy of a permanent spell becomes a token.)

Icecap Tortoise enters with three ice counters on it.
Icecap Tortoise has defender as long as it has an ice counter on it.
{1}{U}: Remove an ice counter from Icecap Tortoise.

[+1]: Up to one target creature gets +2/+0 until end of turn. Each player loses 1 life.
[–X]: Return target creature card with mana value X from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield.
[–7]: For each 1 life target player has less than their starting life total, create a 1/1 black Bird creature token with flying and deathtouch.

{1}, Tap an untapped creature you control: Leaping Dancer gets +0/+1 and gains flying until end of turn. Then if you've activated this ability three or more times this turn, transform Leaping Dancer.

{2}{U}, Remove a counter from a permanent you control: If it was a +1/+1 counter, draw a card. If it was a lore counter, put a +1/+1 counter on Minnow's Accomplice. Activate only as a sorcery.

Play with the top card of your library revealed.
You may cast Elemental spells from the top of your library.

Flying, first strike, haste
Whenever you gain life, you may have Gisela, Blade of Morning deal that much damage to any target. Do this only once each turn.

Exile up to three target cards from a single graveyard. Create a tapped 2/2 colorless Spirit creature token.

At the beginning of your upkeep, you may discard a card. If you do, draw a card.
At the beginning of your end step, Choking Dunes deals X damage to any target, where X is the number of land cards in your graveyard.

Enchant opponent
When Down with the Ship enters, enchanted player discards a card unless they sacrifice a creature.
{1}{B}, Sacrifice Down with the Ship: Return target creature card from your graveyard to your hand.

({T}: Add {U}, {B}, or {R}.)
Bleak Dominion enters tapped.

Add two mana in any combination of colors. (Then exile this card. You may cast the creature later from exile.)

Whenever equipped creature attacks, it gains deathtouch until end of turn.
Sacrifice Bandit's Dagger: Target player dealt damage by equipped creature this turn reveals their hand. You choose a nonland card from it. That player discards that card.
Equip {2}

Codex — Little Pig; Charging Cassowary; The Lonely Hunter; Shadowlurk; Blood Constrictor. (As this enters, conjure its contents into a shuffled face-up additional library.)
You may cast Adventures of this codex's contents from your graveyard.

Siphon (Each -1/-1 counter you put on your creatures up to their remaining toughness while casting this pays for {1}.)
Draw three cards.

Target permanent you control gains hexproof and indestructible until end of turn. You gain 2 life.

Whenever a player casts a non-Dwarf spell or plays a non-Mountain land, this creature deals 2 damage to that player.
{1}{R}, Discard this card: Search your library for a Dwarf or Mountain card, reveal it, put it into your hand, then shuffle.

When Alaina enters, each opponent loses X life and you gain X life, where X is the number of Clerics you control.
{W}{B}, Pay 2 life: Return Alaina from your graveyard to your hand. Activate only if you have more life than your starting life total.

Flying (This creature can't be blocked except by creatures with flying or reach.)
{B}: Night Screecher gains deathtouch until end of turn. (Any amount of damage this deals to a creature is enough to destroy it.)

When Teikoku Captain enters, create a 2/2 colorless Spirit creature token.
Colorless creatures you control have first strike.

Destroy target creature unless its controller pays {3}.

Choose target creature you control. Exile each creature you control. For each creature exiled this way, create a token that's a copy of the chosen creature, except it has haste and isn't legendary. At the beginning of the next end step, sacrifice those tokens, then return the exiled cards to the battlefield tapped.

Reveal the top four cards of your library. You may put a creature card and/or a land card from among them into your hand. Put the rest into your graveyard, then discard a card if two cards were put into your hand this way.

At the beginning of your end step, if you own a card in exile, create a 1/1 white Spirit creature token with flying.

Flying
Civilized — Whenever Aven Supervisor deals combat damage to a player, if you control an artifact, a creature, and an enchantment, you may draw a card. If you do, discard a card.