Talent of the Telepath

Mind's Desire let you replay your own deck for free; this is the predatory inversion, stealing spells off an opponent's library instead of yours. The seven-card dig is window dressing for the casting clause: any instant or sorcery in the top seven is yours, and the rest go to the graveyard, so you mill the spells you cannot use while pocketing the one you can. That asymmetry is what makes the effect feel mean. You are not just disrupting a draw step, you are converting an opponent's threats and answers into your own tempo, then stripping the next several turns of action off the top. Spell mastery is the lever that decides whether this is a midrange value play or a haymaker: clear the two-spell threshold in your own graveyard and a single cast becomes two, which against a control or combo deck can mean lifting their counterspell and their wincon in the same breath. The catch is that you are at the mercy of what they happen to be holding above their library; against a creature-heavy board you may reveal seven things you cannot touch and accomplish nothing but a mill. It rewards a deck already built to fuel its own graveyard, which is also the deck most likely to have spell mastery online when it casts this.