Mind Control effects are cool too, and this combines both
A lot of modern planeswalkers, like the new Ugin and Elspeth from this very set, do have passive abilities that will continue to function while Conqueror is out
This is exactly what Draining Whelk does, and the fun only begins if you get to pair it with blink effects like Ephemerate or Ghostly Flicker
Its a great Pyroclasm, and the fact that it hits artifacts makes this card an excellent control piece across multiple formats including Standard, Pioneer, and Commander
As the combination of draft and set boosters (both of which you may still see on store shelves), play boosters cost a bit more than previous draft boosters, but that's because there's a decent chance of getting more rares
Its also a testament to the inherent explosiveness of the sacrifice playstyle that almost any value-adding trigger quickly becomes game breaking when coupled to it