Put any number of target noncreature cards from your graveyard on top of your library in any order.
Draw a card, then exile Long-Lost Legacy.

Create X blue Shrine enchantment tokens named Unmarked Shrine with “At the beginning of your upkeep, each opponent mills a card.”
{1}{U}, Exile Lost to Memory from your graveyard: Draw two cards. Activate only if an opponent has eight or more cards in their graveyard.

Put a +1/+1 counter on target creature. It gets +0/+2 until end of turn.

Sacrifice a Treasure: Put a loyalty counter on Marilye, Dreaming Big.
[+1]: Draw a card, then discard a card. If you discarded a nonland card this way, create a tapped Treasure token.
[–3]: Gain control of target artifact. It becomes a Treasure artifact, loses all other types, and loses all abilities except for activated mana abilities.
[–8]: Target opponent chooses a nonland permanent they control. You gain control of the rest.

Create two 1/1 blue Wizard creature tokens with prowess.

Target artifact or creature's owner puts it on the top or bottom of their library.
Flashback {5}{U}{U}

Return target creature or enchantment to its owner's hand. If that permanent's controller has eight or more cards in their graveyard, its owner puts it on the top or bottom of their library instead.

Tap up to two target creatures. Put a stun counter on each of them.

Counter target noncreature spell.

This spell costs {2} less to cast if it targets an artifact.
Gain control of target nonland permanent until the end of your next turn.

Enchant creature
Enchanted creature has “Whenever this creature deals combat damage to a player or planeswalker, scry 1, then draw a card.”

Flash
When Omen of Deception enters, counter target spell unless its controller pays {2}.
{2}{U}, Sacrifice Omen of Deception: Scry 2.

Whenever you draw a card, put a foreshadow counter on this enchantment.
Remove eight foreshadow counters from this enchantment: Create an 8/8 blue Kraken creature token.
Cycling {2}

Enchant creature
Whenever enchanted creature attacks, put a +1/+1 counter on it. Then if it has three or more +1/+1 counters on it, sacrifice Ordeal of Ephara.
When you sacrifice Ordeal of Ephara, return up to two target nonland permanents to their owner's hand.

Target creature you control gains hexproof until end of turn. When a nonmana ability of that creature is next activated or triggered this turn, copy it. You may choose new targets for the copy.

Counter target spell. That spell's controller reveals their hand. Choose any number of nonland cards from it. That player puts those cards on the bottom of their library in any order, then draws that many cards.

Draw a card.
Corrupt — If you control a permanent with greater mana value than this spell, surveil 2.

This spell costs {1} less to cast for each tapped creature you control.
Counter target spell unless its controller pays {X}.

Amity — When you cast this spell, copy it if you attacked with exactly two creatures this turn. You may choose new targets for the copy.
Target creature gets +0/+2 and gains hexproof until end of turn.

When Primordial Seas enters and whenever you cast a spell, create a token that's a copy of another target permanent you control.

Whenever you cast a spell, you may pay {X}, where X is that spell's mana value. If you do, copy it. You may choose new targets for the copy. Do this only once each turn.

Exchange control of target spell or creature you control and target spell or creature an opponent controls. Controllers of spells exchanged this way may choose new targets for them.

Whenever this Subroutine runs, each player may shuffle their hand and graveyard into their library, then draw seven cards.

Whenever you attack, create a tapped and attacking token that's a copy of target attacking creature, except it isn't legendary. Sacrifice it at the beginning of the next end step.

Draw three cards. Then discard a card unless a Subroutine ran under your control this turn.