Shadow of the Goblin

Unreliable Visions — At the beginning of your first main phase, discard a card. If you do, draw a card.
Undying Vengeance — Whenever you play a land or cast a spell from anywhere other than your hand, this enchantment deals 1 damage to each opponent.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Stormcatch Mentor

Haste
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Instant and sorcery spells you cast cost {1} less to cast.

Impending Flux

Paradox — Impending Flux deals X damage to each opponent and each creature they control, where X is 1 plus the number of spells you've cast from anywhere other than your hand this turn.
Foretell {1}{R}{R} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

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.)

Memory Worm

Paradox — Whenever you cast a spell from anywhere other than your hand, this creature deals 2 damage to target player. That player discards a card, then draws a card. Put a +1/+1 counter on this creature.

Experimental Augury

Look at the top three cards of your library. Put one of them into your hand and the rest on the bottom of your library in any order. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Wrenn's Resolve

Exile the top two cards of your library. Until the end of your next turn, you may play those cards.

Talisman of Creativity

{T}: Add {C}.
{T}: Add {U} or {R}. This artifact deals 1 damage to you.

Otterball Antics

Create a 1/1 blue and red Otter creature token with prowess. If this spell was cast from anywhere other than your hand, put a +1/+1 counter on that creature. (Whenever you cast a noncreature spell, a creature with prowess gets +1/+1 until end of turn.)
Flashback {3}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Fortune Teller's Talent

(Gain the next level as a sorcery to add its ability.)
You may look at the top card of your library any time.
{3}{U}: Level 2
As long as you've cast a spell this turn, you may play cards from the top of your library.
{2}{U}: Level 3
Spells you cast from anywhere other than your hand cost {2} less to cast.

Reckless Impulse

Command Tower

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

Clockwork Percussionist

Haste
When this creature dies, exile the top card of your library. You may play it until the end of your next turn.

See the Truth

Look at the top three cards of your library. Put one of those cards into your hand and the rest on the bottom of your library in any order. If this spell was cast from anywhere other than your hand, put each of those cards into your hand instead.

War of the Last Alliance

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — Search your library for a legendary creature card, reveal it, put it into your hand, then shuffle.
III — Creatures you control gain double strike until end of turn. The Ring tempts you.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Sol Ring

Ragavan, Nimble Pilferer

Whenever Ragavan deals combat damage to a player, create a Treasure token and exile the top card of that player's library. Until end of turn, you may cast that card.
Dash {1}{R} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)

Surge of Brilliance

Paradox — Draw a card for each spell you've cast this turn from anywhere other than your hand.
Foretell {1}{U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Talisman of Conviction

{T}: Add {C}.
{T}: Add {R} or {W}. This artifact deals 1 damage to you.

Arcane Signet

Ghost-Spider

Flying, vigilance, haste
Whenever you play a land from exile or cast a spell from exile, put a +1/+1 counter on Ghost-Spider.
Remove two counters from Ghost-Spider: Exile the top card of your library. You may play that card this turn.

Gwen Stacy

When Gwen Stacy enters, exile the top card of your library. You may play that card for as long as you control this creature.
{2}{U}{R}{W}: Transform Gwen Stacy. Activate only as a sorcery.

Gwen Stacy // Ghost-Spider

Cori-Steel Cutter

Equipped creature gets +1/+1 and has trample and haste.
Flurry — Whenever you cast your second spell each turn, create a 1/1 white Monk creature token with prowess. You may attach this Equipment to it. (Whenever you cast a noncreature spell, the token gets +1/+1 until end of turn.)
Equip {1}{R}

Spider-Verse

The "legend rule" doesn't apply to Spiders you control.
Whenever you cast a spell from anywhere other than your hand, you may copy it. If you do, you may choose new targets for the copy. If the copy is a permanent spell, it gains haste. Do this only once each turn.

Mountain

The Lost and the Damned

Whenever a land you control enters from anywhere other than your hand or you cast a spell from anywhere other than your hand, create a 3/3 red Spawn creature token.

Plains

Talisman of Progress

{T}: Add {C}.
{T}: Add {W} or {U}. This artifact deals 1 damage to you.

Eruth, Tormented Prophet

If you would draw a card, exile the top two cards of your library instead. You may play those cards this turn.

Land Tax

At the beginning of your upkeep, if an opponent controls more lands than you, you may search your library for up to three basic land cards, reveal them, put them into your hand, then shuffle.

Expressive Iteration

Look at the top three cards of your library. Put one of them into your hand, put one of them on the bottom of your library, and exile one of them. You may play the exiled card this turn.

Island

Vega, the Watcher

Flying
Whenever you cast a spell from anywhere other than your hand, draw a card.