To set a scheme in motion, move it off the top of your scheme deck if it’s on top of your scheme deck and turn it face up if it isn’t face up. That scheme is considered to have been set in motion even if neither of these actions was performed on it.
July 3, 2020 · Core Set 2021
The listed choices may be objects, words with no rules meaning that are each connected to a different effect, or other variables relevant to the resolution of the spell or ability.
April 27, 2018 · Dominaria
rule 701.32b not present in this release
September 30, 2016 · Kaladesh
Any time you have priority, you may turn a manifested permanent you control face up. This is a special action that doesn’t use the stack (see rule 115.2b). To do this, show all players that the card representing that permanent is a creature card and what that card’s mana cost is, pay that cost, then turn the permanent face up. The effect defining its characteristics while it was face down ends, and it regains its normal characteristics. (If the card representing that permanent isn’t a creature card or it doesn’t have a mana cost, it can’t be turned face up this way.)