Brilliant Ultimatum

Exile the top five cards of your library. An opponent separates those cards into two piles. You may play lands and cast spells from one of those piles. If you cast a spell this way, you cast it without paying its mana cost.

Jace, Architect of Thought

+1: Until your next turn, whenever a creature an opponent controls attacks, it gets -1/-0 until end of turn.
−2: Reveal the top three cards of your library. An opponent separates those cards into two piles. Put one pile into your hand and the other on the bottom of your library in any order.
−8: For each player, search that player's library for a nonland card and exile it, then that player shuffles. You may cast those cards without paying their mana costs.

Gollum, Scheming Guide

Whenever Gollum, Scheming Guide attacks, look at the top two cards of your library, put them back in any order, then choose land or nonland. An opponent guesses whether the top card of your library is the chosen kind. Reveal that card. If they guessed right, remove Gollum from combat. Otherwise, you draw a card and Gollum can't be blocked this turn.

Fractured Identity

Exile target nonland permanent. Each player other than its controller creates a token that's a copy of it.

Fight or Flight

At the beginning of combat on each opponent's turn, separate all creatures that player controls into two piles. Only creatures in the pile of their choice can attack this turn.

Fracture

Destroy target artifact, enchantment, or planeswalker.

Make an Example

Each opponent separates the creatures they control into two piles. For each opponent, you choose one of their piles. Each opponent sacrifices the creatures in their chosen pile. (Piles can be empty.)

Triumph of Saint Katherine

Lifelink
Praesidium Protectiva — When Triumph of Saint Katherine is put into your graveyard from the battlefield, exile it and the top six cards of your library in a face-down pile. If you do, shuffle that pile and put it back on top of your library.
Miracle {1}{W} (You may cast this card for its miracle cost when you draw it if it's the first card you drew this turn.)

Truth or Tale

Reveal the top five cards of your library and separate them into two piles. An opponent chooses one of those piles. Put a card from the chosen pile into your hand, then put all other cards revealed this way on the bottom of your library in any order.

Boneyard Parley

Exile up to five target creature cards from graveyards. An opponent separates those cards into two piles. Put all cards from the pile of your choice onto the battlefield under your control and the rest into their owners' graveyards.

Liliana of the Veil

+1: Each player discards a card.
−2: Target player sacrifices a creature.
−6: Separate all permanents target player controls into two piles. That player sacrifices all permanents in the pile of their choice.

Do or Die

Separate all creatures target player controls into two piles. Destroy all creatures in the pile of that player's choice. They can't be regenerated.

Sphinx of Clear Skies

Flying, ward {2}
Domain — Whenever Sphinx of Clear Skies deals combat damage to a player, reveal the top X cards of your library, where X is the number of basic land types among lands you control. An opponent separates those cards into two piles. Put one pile into your hand and the other into your graveyard. (Piles can be empty.)

Adric, Mathematical Genius

{2}{U}, {T}: Copy target activated or triggered ability you control. You may choose new targets for the copy.
Ultimate Sacrifice — {1}{U}, Sacrifice Adric: Counter target activated or triggered ability.
Doctor's companion (You can have two commanders if the other is the Doctor.)

Atris, Oracle of Half-Truths

Menace
When Atris, Oracle of Half-Truths enters, target opponent looks at the top three cards of your library and separates them into a face-down pile and a face-up pile. Put one pile into your hand and the other into your graveyard.

Epiphany at the Drownyard

Reveal the top X plus one cards of your library and separate them into two piles. An opponent chooses one of those piles. Put that pile into your hand and the other into your graveyard.

Sphinx of Uthuun

Flying
When Sphinx of Uthuun enters, reveal the top five cards of your library. An opponent separates those cards into two piles. Put one pile into your hand and the other into your graveyard.

Damn

Destroy target creature. A creature destroyed this way can't be regenerated.
Overload {2}{W}{W} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Vindicate

The Seventh Doctor

Whenever The Seventh Doctor attacks, choose a card in your hand. Defending player guesses whether that card's mana value is greater than the number of artifacts you control. If they guessed wrong, you may cast it without paying its mana cost. If you don't cast a spell this way, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Fortune's Favor

Target opponent looks at the top four cards of your library and separates them into a face-down pile and a face-up pile. Put one pile into your hand and the other into your graveyard.

Jeskai Infiltrator

Jeskai Infiltrator can't be blocked as long as you control no other creatures.
When Jeskai Infiltrator deals combat damage to a player, exile it and the top card of your library in a face-down pile, shuffle that pile, then manifest those cards. (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.)

Liar's Pendulum

{2}, {T}: Choose a card name. Target opponent guesses whether a card with that name is in your hand. You may reveal your hand. If you do and your opponent guessed wrong, draw a card.

Fact or Fiction

Reveal the top five cards of your library. An opponent separates those cards into two piles. Put one pile into your hand and the other into your graveyard.

Ghastly Conscription

Exile all creature cards from target player's graveyard in a face-down pile, shuffle that pile, then manifest those cards. (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.)

Death or Glory

Separate all creature cards in your graveyard into two piles. Exile the pile of an opponent's choice and return the other to the battlefield.

Sauron's Ransom

Choose an opponent. They look at the top four cards of your library and separate them into a face-down pile and a face-up pile. Put one pile into your hand and the other into your graveyard. The Ring tempts you.