20 Sept 2016
If an effect copies Morbid Curiosity, the controller of the copy will draw the same number of cards as determined by the original. Its controller can't and doesn't have to sacrifice a permanent.
20 Sept 2016
If a permanent has {X} in its mana cost, X is considered to be 0.
20 Sept 2016
To determine how many cards to draw, use the mana value of the permanent immediately before you sacrificed it.