I like the concept. It is really fitting for a virtual card game.
But it wouldn't make the ladder more playable (in the "balanced" sense) since it will bring its own OP cards and combo plays. Your main reason for this is teching. But have you been "Teched" before? Thus, it will become the new "cancer" of the meta, and what will counter this? A tech for the tech? xD
Maybe if this worked with a Legendary like Prince Malchezaar and Benedictus. "Start of the game: Put your embedded cards into your deck"
*Obs: we don't have interaction of Discovery in "Cast when drawn" because it may trigger in the opponent's turn.