msem-instigator

As The Mistake enters, choose a card name.
Activated abilities of sources with the chosen name can't be activated unless they're mana abilities.
Unveil {5} ({5}: Transform this. Unveil only as a sorcery.)

The Mythical Zhiwu enters with four +1/+1 counters on it.
{1}, Remove a +1/+1 counter from a creature you control: Target creature gets -1/-1 until end of turn. Activate only as a sorcery.
{1}, Remove a +1/+1 counter from a creature you control: Each opponent loses 1 life and you gain 1 life.

The Oltenen Emissary is all colors.
You may pay {W}{U}{B}{R}{G} rather than pay the mana cost for spells that you cast. When you do, you may cast spells without paying their mana costs until end of turn.

Each planeswalker you control is an Okus in addition to its other types.
[–1]: Search your library for a planeswalker card or an Aura card with enchant planeswalker, reveal it, and put it into your hand, then shuffle.
The Paragon of Haberdashery can be your commander. If it is, it's all colors.

When The Raven Queen of Fretport enters, put a -1/-1 counter on each of any number of target creatures.
{2}{U}{B}: Proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)

Flying
Whenever one or more other creatures die for the first time each turn, journey. (To journey, exile the top card of your library face up. Whenever a creature you control deals combat damage to an opponent, put a journeyed card you own into your hand.)

At the beginning of your end step, create a 1/1 colorless Human creature. Put a sacrifice counter on it.
Creature tokens you control with sacrifice counters on them can't attack or block and have “Sacrifice this creature: Add {C}.”

Trample
When The Shepherd of Nowhere enters, each player sacrifices each other nontoken creature they control.
Whenever another nontoken creature you control dies, create a token that's a copy of that creature.

Flying
Spirited (When this creature enters, you may activate one of its activated abilities without paying its costs.)
Harmony — Draw three cards.
{2}{G}{G}: Harmonize. (Trigger up to one harmony of a permanent you control.)

Deathtouch, lifelink
At the beginning of combat on your turn, for each creature your opponents control, you may tap an untapped creature you control. If you do, those creatures fight each other.

Defender
Your maximum hand size is thirteen.
{T}: If you have fewer than thirteen cards in hand, draw cards equal to the difference. Activate only as a sorcery.

Permanent cards in your graveyard have The Undercity Amalgam's Adventure.
Once during each of your turns, you may cast an Adventure spell from your graveyard.

The Unshakable Kian enters with three wish counters on him.
Remove a wish counter from Kian: Choose one. Activate only as a sorcery and only once each turn.
• Kian gains hexproof and trample until your next turn.
• Tap up to three target nonland permanents and put a stun counter on each of them.
• If you have fewer than four cards in hand, draw cards equal to the difference.

[0]: Creatures you control gain haste until end of turn. Whenever a creature attacks this turn, put a loyalty counter on The Warrior Within.
[–1]: Exile the bottom two cards of your library. You may play one of them this turn.
[–6]: Untap each creature that attacked this turn. After this main phase, there is an additional combat phase.

Whenever The Wicker Lord or another Scarecrow you control enters, create a 1/1 black Bird creature token with flying for each Scarecrow you control.
{4}, Sacrifice a Scarecrow: Return target artifact card from your graveyard to the battlefield.

[+2]: The Witch Queens deal 2 damage to each of up to two targets.
[–3]: Gain control of target land and untap it.
[–9]: Each player discards their hand, then draws up to seven cards. The Witch Queens deal damage to each opponent equal to twice the number of cards that player has drawn this turn.

As Theodore Harper, Head Librarian enters, choose Fact or Fiction.
• Fact — Permanent spells you cast cost {1} less to cast. This effect can't reduce the amount of mana a spell costs to cast to less than one mana.
• Fiction — When Theodore Harper enters, return a permanent card from your graveyard to your hand.

Other creatures have haste and attack each combat if able.
Nonland cards in your hand have paranoia {4}. (The owner of a card with paranoia {4} may cast it from their hand for {4} when a permanent they control leaves the battlefield.)

Other untapped creatures have hexproof.
Whenever a creature attacks you, put a +1/+1 counter on a creature you control.

Haste
At the beginning of combat on your turn, create two nonlegendary token copies of Thrice-Clawed Troika. Then for each creature token created this way, create token copies of each permanent attached to Thrice-Clawed Troika and attach them to that creature token. Exile all tokens created this way at end of combat.

Creature tokens you control get +1/+1.
Whenever Thyra, Winter's Warden enters or attacks, you may pay {1}{G/W}. If you do, create Bruga, a legendary 2/2 green and white Wolf creature token.

First strike
If one or more creature tokens would be created under your control, for each of those tokens, you may create three 2/2 green Cat Warrior creature tokens instead.

First mate — Each nonland card in your starting deck is an artifact, a Pirate, or has “artifact,” “Treasure,” or “Pirate” in its printed rules text. (If this card outside the game is your chosen first mate, you may swap it with a card in your opening hand.)
Whenever Tinbeard of the Brine attacks, each opponent loses X life and you gain X life, where X is the number of artifacts you control plus the number of Pirates you control.

At the beginning of combat on your turn, tap Tinchor, put two +1/+1 counters on him, you draw a card, and you lose 1 life.
When Tinchor dies, put his counters on target Human you control.

Your opponents can't search libraries unless they pay {2}.
[+2]: If an opponent has more life than you, you gain 2 life.
[0]: If an opponent controls more creatures than you, you create two 1/1 white Gnome creature tokens.
[–4]: Search your library for a creature card with mana value 2, put it onto the battlefield, then shuffle.