Mystery Booster Playtest Cards 2021

Animate Spell

Flash
Enchant instant or sorcery spell on the stack
When Animate Spell becomes attached to an instant or sorcery, put that card onto the battlefield under its owner's control. It's a creature in addition to its other types with power and toughness each equal to its converted mana cost.
When Animate Spell leaves the battlefield, enchanted card's owner sacrifices it unless they cast it.

Mystery Booster Playtest Cards 2019

Flash
Enchant instant or sorcery spell on the stack
When CARDNAME becomes attached to an instant or sorcery, put that card onto the battlefield under its owner's control. It's a creature in addition to its other types with power and toughness each equal to its converted mana cost.
When CARDNAME leaves the battlefield, enchanted card's owner sacrifices it unless they cast it.