What does the name have to do with the card theme/effect?
What does Nightmare has to do with filling ur opponent's hand with targeted creature?
I dunno, but at the very least it relates to the element. Sound is under (Shockwave), not .
Well, sound moves/travels randomly. Point for Entropy?
To balance this, why not give it a damage cap, like catapult. So perhaps have X be no greater than (ex.) 20.
After applying a cap, the cost should be easier to settle.