Getting two rats for 3 mana and four cards in your graveyard is interesting, and it only gets better from there
You could build a reserve of high power, low toughness sacrifice fodder in order to draw plenty of cards without draining your life away too fast, but then Greven, Predator Captain wouldnt get a proper power bonus
As you can see, Battle for Zendikar Standard is the most expensive Standard on Magic Online since Gatecrash Standard and the results aren't close
So yeah, Paradox Haze gives an enchanted player a second upkeep
These are not scarce enough to hold premium value long-term and don't have the character prestige of Manga Rares
Some people might have been a bit leery, but I lot the creativity of these fifteen cards