For example, your opponent could easily be comfortable with only having 2 powerful monsters on the field, making this card completely useless
If Im not playing a bunch of cloak, morph, or megamorph creatures, Id want enough creatures in my deck so that the odds are pretty good that the other two cloaked cards would include another creature I could flip up
Magus of the Wheel and Painful Truths are two other excellent burst draw, and while I'm not as high on it as others are, Verge Rangers is pretty good too in a deck with almost zero land ramp
Each of the Timelords has a unique effect that activates at the end of the Battle Phase if it has battled, so you can take advantage of them not being destroyed as well as their effects preventing you from taking damage
Meanwhile, even $20 is a ludicrous amount of money to charge for a single greetings card
With a bit of finagling it can copy the stats of any of the other monsters mentioned here, and mid-battle no less