Melek, Izzet Paragon

Play with the top card of your library revealed.
You may cast instant and sorcery spells from the top of your library.
Whenever you cast an instant or sorcery spell from your library, copy it. You may choose new targets for the copy.

Sol Ring

Skyshroud Claim

Search your library for up to two Forest cards, put them onto the battlefield, then shuffle.

Kruphix, God of Horizons

Indestructible
As long as your devotion to green and blue is less than seven, Kruphix isn't a creature.
You have no maximum hand size.
If you would lose unspent mana, that mana becomes colorless instead.

Past in Flames

Each instant and sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost.
Flashback {4}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Brain in a Jar

{1}, {T}: Put a charge counter on this artifact, then you may cast an instant or sorcery spell with mana value equal to the number of charge counters on this artifact from your hand without paying its mana cost.
{3}, {T}, Remove X charge counters from this artifact: Scry X.

Gruul Signet

Izzet Signet

Hypersonic Dragon

Flying, haste
You may cast sorcery spells as though they had flash. (You may cast them any time you could cast an instant.)

Young Pyromancer

Whenever you cast an instant or sorcery spell, create a 1/1 red Elemental creature token.

Simic Signet

Scry 1. (Look at the top card of your library. You may put that card on the bottom.)
Draw a card.

Growth Spiral

Draw a card. You may put a land card from your hand onto the battlefield.

Firemind's Research

Whenever you cast an instant or sorcery spell, put a charge counter on this enchantment.
{1}{U}, Remove two charge counters from this enchantment: Draw a card.
{1}{R}, Remove five charge counters from this enchantment: It deals 5 damage to any target.

Recollect

Return target card from your graveyard to your hand.

Guttersnipe

Whenever you cast an instant or sorcery spell, this creature deals 2 damage to each opponent.

Stolen Goods

Target opponent exiles cards from the top of their library until they exile a nonland card. Until end of turn, you may cast that card without paying its mana cost.

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Riku of Two Reflections

Whenever you cast an instant or sorcery spell, you may pay {U}{R}. If you do, copy that spell. You may choose new targets for the copy.
Whenever another nontoken creature you control enters, you may pay {G}{U}. If you do, create a token that's a copy of that creature.