Mindslaver Taking control of someones turn is a unique effect that has existed since Magics earliest days
Some of the most popular EDH cards (and cards in general) have Showcase versions as their premium printing though, and so I think that now is a good time to be looking at buying some of them
Here are the white cards that utilize the ASCEND mechanic: Of these, Radiant Destiny is the most promising
Card Set(s) -ADVENTURE ON KAMI'S ISLAND- [OP15-EB04] CARD VIEW OP15-117 | UC | EVENT Heso
Flying, trample, protection from white and from blue : Akroma gets +1/+0 until end of turn
Out of the three of them, I think Jace, Wielder of Mysteries is the perfect mix of usefulness and power: he can be played early in the game for advantage, but he also encourages combat as he can be attacked directly