msem-instigator

When Sandborn Mage enters, you may return target instant or sorcery card from your graveyard to your hand.
Mirage {2}{U}{U} (You may cast this spell as though it had flash for its mirage cost. If you do, sacrifice it at the beginning of the next cleanup step.)

Draw three cards, then manifest a card from your hand. (To manifest a card, put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)

Flying
When Scion of Torrents enters, you may return target nonland permanent to its owner's hand.
Whenever an Island you control enters, you may aetherize Scion of Torrents. (To aetherize, create a token that's a copy of it, then exile that token.)

{U}: Sea Strider gets +1/-1 until end of turn.
{U}: Sea Strider gets -1/+1 until end of turn.

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.

Untap all permanents you control during each other player's untap step.

Flash
Menagerie — When Seven Seas Scourge enters, if there are five or more creature types among creatures you control, counter target spell with mana value 4 or less.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever you cast a noncreature spell, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)

Flying
When Sharp-Eyed Wingmate enters, you may return target creature to its owner's hand.

Vigilance
Whenever one or more creatures you control deals combat damage to a player, you may discard a card. If you do, create a Function token with “Draw two cards.” (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)

{8}{U}{U}: Monstrosity 5. (If this creature isn't monstrous, put five +1/+1 counters on it and it becomes monstrous.)
When Shipway Whale becomes monstrous, target player exiles all cards in their library, then shuffles their graveyard into their library.

{3}{U}{U}: Monstrosity 4. (If this creature isn't monstrous, put four +1/+1 counters on it and it becomes monstrous.)
When Shorecrash Octopus becomes monstrous, return target instant or sorcery card from your graveyard to your hand.

Flying, vigilance

This spell can't be countered.
{U}: Exile Skulkling. Return it to the battlefield under its owner's control at the beginning of the next end step.
{1}{U}: Until end of turn, Skulkling gets +1/-1 and can't be blocked.
{3}{U}: Draw a card. Create a 1/1 blue Rogue creature token.

Flying
If a nonland permanent an opponent controls would be returned to its owner's hand, instead gain control of it for as long as you control Sphinx Paramount.

Flying, ward {3}
Whenever Sphinx of Myriad Futures attacks, look at the top three cards of your library and reveal one of them. The defending player may have you put the revealed card into your hand. If they don't, put the other two cards into your hand. Then put the remaining cards into your graveyard.

Flying
Whenever Spirit of Vitriol attacks, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
Discard a card: Spirit of Vitriol gains hexproof until end of turn. Tap it.

This spell can't be countered.
Flying
Dominance — Whenever Stormwing Ultrateryx becomes the target of a spell an opponent controls, if you control the creature with the greatest power or tied for the greatest power, counter that spell.

Choose up to one creature. Return the rest to their owners' hands.

Flying, prowess
Whenever Surveyor of Skies attacks, you may return a permanent you control to its owner's hand.

(As this Discovery enters and after your draw step, add a progress counter. Stop after you've discovered.)
Archive 6 (As this enters, shuffle the top six cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
Draw a card from each of your libraries.
discover — When you draw the last card from the archived library, create a 4/4 blue Sphinx Wizard creature token with flying.

Flying
When Tattered Wisp enters, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.

Flying
Territorial Drake has hexproof as long as it's untapped.
Whenever Territorial Drake becomes tapped, scry 2.
Whenever Territorial Drake becomes untapped, draw a card.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
Flash
Draw three cards.
You may cast a spell with mana value less than or equal to the number of lore counters on The Infinite Calls to Marva from your hand without paying its mana cost.

Whenever you draw a card, you may have target opponent exile the top card of their library face down.
You may look at and play cards exiled with Thought Siphon, and you may spend blue mana as though it were mana of any color to cast them.