Historical Rules · 25 January 2019
Rule 904.9
Official source text from the 25 January 2019 Rules release
Immediately after the archenemy's precombat main phase begins during each of their turns, that player moves the top card of their scheme deck off that scheme deck and turns it face up. This is called "setting that scheme in motion." (See rule 701.24.) This turn-based action doesn't use the stack. Abilities of that scheme card that trigger "When you set this scheme in motion" trigger.