Drawing an average four to six cards for five mana is a backbreaker in limited, and having this in the common slot to boot didn't hurt matters much
You can use it as a sort of protective spell by responding to an opponents removal spell and copying the creature they attempt to kill, or surprise a creature like Niv-Mizzet, Parun in combat to trade
Thats true of most of the cycle, but this one doesnt affect the game state at all, and the set has little else to support a mill engine
I wont bury the lede on this one, its still a very good card, and should probably be played over any three-mana counter or two-mana conditional one
though you will have Time Lords in the form of Missy, The Master and The Valeyard, at least
Garruk, Caller of Beasts 4 Potent card draw and some mild bonus ramp potential too