A colorless shapeshifter 7/7 with changeling for seven mana, when Morophon enters the battlefield, its controller chooses a creature type
The idea of an impossibly large mansion plays into the horror trope space we were exploring, so that's what got greenlit: A new plane 70's and 80's horror film inspired (and the technology level that came with that) A set that takes place solely inside a single mansion In exploratory design, the first question we asked was, "How do we keep this world from mechanically stepping on the toes of the planes of Innistrad and New Phyrexia?" Early on, we realized the horror we wanted to evoke relied on a specific mood and tone
Reliquary Tower can make sure your hand never gets too full (something that can be a problem for Izzet mages) and Mystic Sanctuary offers a return path for used instants and sorceries
The Sprite is one generic mana cheaper, but its status as an uncommon versus a common can explain the mana cost
Fast+Furious is a very impactful card in some match up and you can play it
Obviously, considering the high cost of many dinosaur cards, this is an incredibly useful ability