The Valeyard

If an opponent would face a villainous choice, they face that choice an additional time. (They can make the same or different choices.)
While voting, you may vote an additional time.

River Song

Meet in Reverse — You draw cards from the bottom of your library rather than the top.
Spoilers — Whenever an opponent scries, surveils, or searches their library, put a +1/+1 counter on River Song. Then River Song deals damage to that player equal to its power.

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

Force of Vigor

If it's not your turn, you may exile a green card from your hand rather than pay this spell's mana cost.
Destroy up to two target artifacts and/or enchantments.

Hidden Blade

Flash
When Hidden Blade enters, attach it to target creature you control. If that creature is an Assassin, it gains deathtouch until end of turn.
Equipped creature gets +1/+0 and has first strike.
Equip {2}

Anafenza, Kin-Tree Spirit

Whenever another nontoken creature you control enters, bolster 1. (Choose a creature with the least toughness among creatures you control and put a +1/+1 counter on it.)

Solitude

Flash
Lifelink
When Solitude enters, exile up to one other target creature. That creature's controller gains life equal to its power.
Evoke—Exile a white card from your hand.

Giant Solifuge

({R/G} can be paid with either {R} or {G}.)
Trample; haste; shroud (This creature can't be the target of spells or abilities.)

Woodcaller Automaton

Prototype {2}{G}{G} — 3/3 (You may cast this spell with different mana cost, color, and size. It keeps its abilities and types.)
When Woodcaller Automaton enters, if you cast it, untap target land you control. It becomes a Treefolk creature with haste and base power and toughness equal to Woodcaller Automaton's power and toughness. It's still a land.

Savage Order

As an additional cost to cast this spell, sacrifice a creature with power 4 or greater.
Search your library for a Dinosaur creature card, put it onto the battlefield, then shuffle. It gains indestructible until your next turn.

Thought Vessel

You have no maximum hand size.
{T}: Add {C}.

Dino DNA

Imprint — {1}, {T}: Exile target creature card from a graveyard. Activate only as a sorcery.
{6}: Create a token that's a copy of target creature card exiled with Dino DNA, except it's a 6/6 green Dinosaur creature with trample. Activate only as a sorcery.

Korvold, Gleeful Glutton

This spell costs {1} less to cast for each card type among permanents you've sacrificed this turn.
Flying, trample, haste
Whenever Korvold deals combat damage to a player, put X +1/+1 counters on Korvold and draw X cards, where X is the number of permanent types among cards in your graveyard.

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Underworld Connections

Enchant land
Enchanted land has "{T}, Pay 1 life: Draw a card."

Sol Ring

Mana Drain

Counter target spell. At the beginning of your next main phase, add an amount of {C} equal to that spell's mana value.

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

The Eleventh Doctor

I. AM. TALKING! — Whenever The Eleventh Doctor deals combat damage to a player, you may exile a card from your hand with a number of time counters on it equal to its mana value. If it doesn't have suspend, it gains suspend.
{2}: Target creature with power 3 or less can't be blocked this turn.

Radha, Heart of Keld

During your turn, Radha, Heart of Keld has first strike.
You may look at the top card of your library any time, and you may play lands from the top of your library.
{4}{R}{G}: Radha gets +X/+X until end of turn, where X is the number of lands you control.

Arcane Signet

As Foretold

At the beginning of your upkeep, put a time counter on As Foretold.
Once each turn, you may pay {0} rather than pay the mana cost for a spell you cast with mana value X or less, where X is the number of time counters on As Foretold.

Muerra, Trash Tactician

At the beginning of your first main phase, add {R} or {G} for each Raccoon you control.
Whenever you expend 4, you gain 3 life. (You expend 4 as you spend your fourth total mana to cast spells during a turn.)
Whenever you expend 8, exile the top two cards of your library. Until the end of your next turn, you may play those cards.

Flubs, the Fool

You may play an additional land on each of your turns.
Whenever you play a land or cast a spell, draw a card if you have no cards in hand. Otherwise, discard a card.

Flusterstorm

Counter target instant or sorcery spell unless its controller pays {1}.
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

Sneak Attack

{R}: You may put a creature card from your hand onto the battlefield. That creature gains haste. Sacrifice the creature at the beginning of the next end step.

Cultivate

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

The Fourth Doctor

You may look at the top card of your library any time.
Would You Like A...? — Once each turn, you may play a historic land or cast a historic spell from the top of your library. When you do, create a Food token. (Artifacts, legendaries, and Sagas are historic.)