And I'll probably never understand the problem with making it return to "the" deck rather than "your" deck, like Reverse Time.
The problem with insta-kills is that when you're balancing one effect against both a 1|1 Photon and a 7|50 Titan, you can only make it generally UP or generally OP. deathreign's card passes the bare minimum "is HP taken into account?" test, while this card does not. While it may pass the "it's usually less useful than Lightning or Reverse Time" test, that's far from claiming it's balance-able. Finally, by not even adding it back to the opponent's deck/hand, this card becomes not just an insta-kill, but an insta-exile.
Again, I haven't even gone into the situations where its effect can be read as "take control of target creature", or that this effect is consistently repeatable despite what you might say about it reducing overall deck consistency.