March of the Machine: The Aftermath

Sarkhan, Soul Aflame | Legendary Creature | Human Shaman | Dragon spells you cast cost {1} less to cast. Whenever a Dragon enters the battlefield under your control, you may have Sarkhan, Soul Aflame become a copy of it until end of turn, except its name is Sarkhan, Soul Aflame and it's legendary in addition to its other types. | Eric Wilkerson

Narset, Enlightened Exile | Legendary Creature | Human Monk | Creatures you control have prowess. Whenever Narset, Enlightened Exile attacks, exile target noncreature, nonland card with mana value less than Narset's power from a graveyard and copy it. You may cast the copy without paying its mana cost. | Marie Magny

Niv-Mizzet, Supreme | Legendary Creature | Dragon Avatar | Flying, hexproof from monocolored Each instant and sorcery card in your graveyard that's exactly two colors has jump-start. (You may cast that card from your graveyard by discarding a card in addition to paying its other costs. Then exile it.) | Joshua Raphael