msem-instigator

Vigilance
When Scion of Storms enters, create a 2/2 white Elemental creature token with flying.
Whenever a Plains you control enters, you may aetherize Scion of Storms. (To aetherize, create a token that's a copy of it, then exile that token.)

Flying, haste
Ride {1}{R} ({1}{R}: Transform this and attach it to target creature you control without a Mount. Ride only as a sorcery.)

Flying, haste
Whenever Scourge of the Skies attacks, you may have it deal 5 damage to target creature.

At the beginning of your upkeep, you gain 1 life. Then if your life total is greater than or equal to your starting life total, you gain an additional 1 life and scry 1. Then if your life total is greater than or equal to three times your starting life total, you win the game.

Whenever you play a land, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
{1}{G}{U}{R}, Sacrifice three Clues: Exile cards from the top of your library until you exile three nonland cards. You may cast any number of those cards without paying their mana costs.

As long as a creature you control has flying, creatures you control have flying. The same is true for first strike, double strike, deathtouch, haste, hexproof, indestructible, lifelink, menace, reach, trample, and vigilance.

Reveal the top five cards of your library. Put one of those cards into your hand. Target opponent chooses two of those cards. Exile the chosen cards, then put the rest into your hand.

When Seluriel's Blessing enters, put a +1/+1 counter on each creature you control.
Creatures you control enter with an additional +1/+1 counter on them.
Creatures you control with counters on them have vigilance and indestructible.

[+1]: You gain 1 life. Put a +1/+1 counter on up to one target creature.
[–3]: Exile target creature. Its controller gains life equal to its power.
[–8]: You get an emblem with “Creatures you control get +1/+1 and have double strike and lifelink.”

Deathtouch
{U/B}: Change a target of target spell or ability that targets Serafina to another creature you control.
Whenever Serafina deals damage to a player, at the beginning of the next end step, that player loses life equal to the life they lost this turn.

[+1]: Remove all counters from target permanent.
[+1]: Each opponent discards a card.
[–2]: Exile target creature or planeswalker card from your graveyard with mana value less than or equal to the number of lands you control. If you do, create a token that's a copy of it.
[–7]: Each opponent gets an emblem with “At the beginning of your upkeep, you lose 7 life unless you sacrifice seven permanents.”

This spell can't be countered.
Flying, protection from cryptic
Whenever you cast a cryptic spell, cast a Sphinx spell, or draw a card, investigate.
{T}, Sacrifice ten Clues: You win the game.

[+1]: Create three 1/1 white Warrior creature tokens. They gain haste.
[0]: Until end of turn, each creature and planeswalker you control becomes a 3/3 Warrior creature and gains indestructible. (Permanents don't lose loyalty while they're not a planeswalker.)
[–2]: Choose tapped or untapped. Seto San deals 3 damage to each creature with the chosen attribute.

[+1]: Distribute two +1/+1 counters among any number of target creatures you control.
[–1]: Create two 1/1 white Monk creature tokens.
[–6]: Until your next turn, you choose which creatures attack or block and how those creatures attack or block.

[+1]: Create a 1/1 white Warrior creature token with lifelink. You gain 1 life.
[–2]: Put two +1/+1 counters on target creature. It gains double strike until end of turn.
[–7]: Choose up to three creatures, then destroy the rest.

As long as it's your turn, Seto San is a 3/3 Human Warrior creature with indestructible.
[+1]: Up to one target creature you control gains lifelink until end of turn.
[0]: Create a 1/1 white Warrior creature token.
[–X]: Search your library for an Aura or Equipment card with mana value X and put it onto the battlefield, then shuffle.

[+1]: Create two 1/1 white Warrior creature tokens. You gain 2 life.
[–2]: Destroy each creature with the greatest power or tied for the greatest power among creatures on the battlefield.
[–5]: Creatures you control get +X/+X and gain lifelink until end of turn, where X is the number of creatures you control.

Destroy all creatures.

When Seven Deadly Sins has seven or more sin counters on it, sacrifice it.
{B}{B}, Put a sin counter on Seven Deadly Sins: Destroy target creature. This ability costs {1} more to activate for each sin counter on Seven Deadly Sins.

Destroy target creature or planeswalker. If you controlled a black legendary creature or planeswalker as you cast this spell, that permanent's controller loses X life and you gain X life, where X is that permanent's mana value.

[+1]: Create a 1/1 green Scout creature token. If you control six or more lands, also create a 1/1 white Bird creature token with flying.
[–1]: Reveal the top card of your library. If it's a land card, put it onto the battlefield. Otherwise, put it into your hand.
[–5]: You get an emblem with “Whenever each permanent you control becomes tapped for the first time each turn, untap it.”

Flying
When Sha Long enters, each player chooses an artifact they control, then sacrifices the rest. If they don't control an artifact, they may return an artifact card from their graveyard to the battlefield. Repeat this process for creatures, enchantments, and planeswalkers.

{U}{R}{W}, Discard a card named Sha'Iv, God of Order: Sha'Iv gains indestructible and becomes a God creature in addition to its other types.
Whenever Sha'Iv enters or attacks, choose target creature an opponent controls. Untap it, then tap each other creature that player controls. They don't untap during their controller's next untap step.

When Shala Na enters, each player chooses a creature they control, then sacrifices the rest.
[+1]: Up to one target creature you control gains double strike and haste until end of turn.
[–6]: You get an emblem with “Whenever a creature dies, each opponent loses 2 life.”

[+1]: Up to two target creatures you control each get +1/+0 and gain first strike until end of turn.
[0]: You may sacrifice a creature. If you do, Shala Na, Urshadi Apostate deals 3 damage to any target.
[–3]: Discard your hand, then draw three cards.