This was a reason to splash green into your control deck, or splash white if you were pulling a Mike Pistulnik
I was so concerned with Kain's control effect being downside or needing to hurt the opponent that I hadn't even considered the card could instead switch sides but give you an upside when you gave him away
This is especially true for Golbez, Crystal Collector, who looks pretty powerful, not to mention iconic
Its ceiling is four mana for three treasures and your opponents lose an artifact each, which is a positive exchange in your favour nine times out of ten
Unless youre playing in a super-fast environment in which you absolutely must make a Turn 1 play, theyre nice budget options and should see lots of play
If it had any other effect to supplement it, I think itd be higher on this list