Guilds of Ravnica

Beamsplitter Mage | Creature | Vedalken Wizard | Whenever you cast an instant or sorcery spell that targets only Beamsplitter Mage, if you control one or more other creatures that spell could target, choose one of those creatures. Copy that spell. The copy targets the chosen creature. | Svetlin Velinov

Crackling Drake | Creature | Drake | Flying Crackling Drake's power is equal to the total number of instant and sorcery cards you own in exile and in your graveyard. When Crackling Drake enters the battlefield, draw a card. | Victor Adame Minguez

Goblin Electromancer | Creature | Goblin Wizard | Instant and sorcery spells you cast cost {1} less to cast. | Svetlin Velinov

League Guildmage | Creature | Human Wizard | {3}{U}, {T}: Draw a card. {X}{R}, {T}: Copy target instant or sorcery spell you control with mana value X. You may choose new targets for the copy. | Svetlin Velinov

Niv-Mizzet, Parun | Legendary Creature | Dragon Wizard | This spell can't be countered. Flying Whenever you draw a card, Niv-Mizzet, Parun deals 1 damage to any target. Whenever a player casts an instant or sorcery spell, you draw a card. | Svetlin Velinov

Wee Dragonauts | Creature | Faerie Wizard | Flying Whenever you cast an instant or sorcery spell, Wee Dragonauts gets +2/+0 until end of turn. | Greg Staples

Piston-Fist Cyclops | Creature | Cyclops | Defender As long as you've cast an instant or sorcery spell this turn, Piston-Fist Cyclops can attack as though it didn't have defender. | Wayne Reynolds

Chamber Sentry | Artifact Creature | Construct | Chamber Sentry enters the battlefield with a +1/+1 counter on it for each color of mana spent to cast it. {X}, {T}, Remove X +1/+1 counters from Chamber Sentry: It deals X damage to any target. {W}{U}{B}{R}{G}: Return Chamber Sentry from your graveyard to your hand. | Adam Paquette