targeting a pillar wouldnt be very useful, its ability would not be altered.
if you target a shard, the cost will become set to your mark rather than random.
nightmaring/fractaling a changed creature will result in the creature of the new element being produced
using this on a fractal, miracle or any other card with a quanta drain should be adjusted to drain the new element for balancing purposes
I've always thought that fire pillars generate fire, so if you changed it to water, it should generate water.
Wait, target shard? Ooooh. I see. Didn't read that you could target cards in your own hand. My bad.
I'm not sure I agree with this. I prefer to see only that one specific creature "changed". If you nightmare'd a fire vampire, let's say, then the game also needs to create a life vampire, water vampire, aether vampire, basically 11 other elements of each creature.
I'd still go with 2|1 cost. But that is just me~ This is your card.