March of the Machine

Halo Forager | Creature | Faerie Rogue | Flying When Halo Forager enters the battlefield, you may pay {X}. When you do, you may cast target instant or sorcery card with mana value X from a graveyard without paying its mana cost. If that spell would be put into a graveyard, exile it instead. | Kevin Sidharta

Invasion of Amonkhet // Lazotep Convert | Battle // Creature | Siege // Zombie | (As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.) When this Siege enters, each player mills three cards, then each opponent discards a card and you draw a card. (To mill three cards, a player puts the top three cards of their library into their graveyard.) // You may have this creature enter as a copy of any creature card in a graveyard, except it's a 4/4 black Zombie in addition to its other colors and types. | Jokubas Uogintas

Mutagen Connoisseur | Creature | Vedalken Mutant | Flying, vigilance Mutagen Connoisseur gets +1/+0 for each transformed permanent you control. | Alex Brock

Stormclaw Rager | Creature | Ogre Warrior | {1}, Sacrifice another creature or artifact: Put a +1/+1 counter on Stormclaw Rager and draw a card. Activate only as a sorcery. | Nicholas Elias

Elvish Vatkeeper | Creature | Phyrexian Elf | When Elvish Vatkeeper enters the battlefield, incubate 2. (Create an Incubator token with two +1/+1 counters on it and "{2}: Transform this artifact." It transforms into a 0/0 Phyrexian artifact creature.) {5}: Transform target Incubator token you control. Double the number of +1/+1 counters on it. | Nicholas Gregory