This static ability just states restriction on casting the second part of the card
I typically run Perplexing Test in token decks to disrupt my nontoken opponents, but just having an instant-speed board wipe can be valuable for decks that want to hold up mana each turn
Then you have the card's effect: in Gifts Ungiven, you search your own deck for cards, whereas in Gifts Given you search your opponent's deck for four cards
As MTG shifts towards decks that play more to the board in a tempo game, its common to see blue decks that rely on creature and permanent loops do well, using cards like Stormchaser's Talent and Quantum Riddler as blink targets and cards like Boomerang Basics as engines
So, if youre looking to pick up the pre-con, Endless Punishment, Valgavoth, Harrower of Souls, then you can head on over to Classroom Caf in Uptown, as thats where we got our Valgavoth deck from
Its a tragically common defect in many players logic circuits that they cannot comprehend the notion that just because something has never happened before, it might still happen someday