Wild-Magic Sorcerer

The first spell you cast from exile each turn has cascade. (When you cast your first spell from exile, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)

Rhystic Study

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

Volcanic Island

Badlands

Ancient Tomb

{T}: Add {C}{C}. Ancient Tomb deals 2 damage to you.

Thran Dynamo

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Chromatic Lantern

Lands you control have "{T}: Add one mana of any color."
{T}: Add one mana of any color.

Izzet Signet

Thermo-Alchemist

Defender
{T}: Thermo-Alchemist deals 1 damage to each opponent.
Whenever you cast an instant or sorcery spell, untap Thermo-Alchemist.

Dark Ritual

Reflecting Pool

{T}: Add one mana of any type that a land you control could produce.

Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.

Sol Ring

Etali, Primal Storm

Whenever Etali attacks, exile the top card of each player's library, then you may cast any number of spells from among those cards without paying their mana costs.

Arcane Signet

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

Commander's Sphere

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

Underground Sea

Maestros Theater

When Maestros Theater enters, sacrifice it. When you do, search your library for a basic Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle and you gain 1 life.

Mizzix, Replica Rider

Flying
Whenever you cast a spell from anywhere other than your hand, you may pay {1}{U/R}. If you do, copy that spell and you may choose new targets for the copy. If the copy is a permanent spell, it gains haste and "At the beginning of your end step, sacrifice this permanent." (A copy of a permanent spell becomes a token.)

Reliquary Tower

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

Abaddon the Despoiler

Trample
Mark of Chaos Ascendant — During your turn, spells you cast from your hand with mana value X or less have cascade, where X is the total amount of life your opponents have lost this turn.

Cascade Bluffs

{T}: Add {C}.
{U/R}, {T}: Add {U}{U}, {U}{R}, or {R}{R}.

Worn Powerstone

Worn Powerstone enters tapped.
{T}: Add {C}{C}.

Prosper, Tome-Bound

Deathtouch
Mystic Arcanum — At the beginning of your end step, exile the top card of your library. Until the end of your next turn, you may play that card.
Pact Boon — Whenever you play a card from exile, create a Treasure token.

Chandra, Torch of Defiance

+1: Exile the top card of your library. You may cast that card. If you don't, Chandra, Torch of Defiance deals 2 damage to each opponent.
+1: Add {R}{R}.
−3: Chandra, Torch of Defiance deals 4 damage to target creature.
−7: You get an emblem with "Whenever you cast a spell, this emblem deals 5 damage to any target."