Each phenomenon card has a triggered ability that triggers when you encounter it. “When you encounter [this phenomenon]” means “When you move this card off a planar deck and turn it face up.”
July 23, 2021 · Adventures in the Forgotten Realms
The owner of a vanguard card is the player who started the game with it in the command zone. The controller of a face-up vanguard card is its owner.
July 1, 2012 · Magic 2013
The owner of a scheme card is the player who started the game with it in the command zone. The controller of a face-up scheme card is its owner.