Can you tell me the rulings for Noxious Dragon?
user
0. A face-down creature has a mana value of 0. However, its mana value changes when it's turned face up. Thus, if a creature is turned face up in response to being targeted by Noxious Dragon's ability, it may become an illegal target.
1. If a creature on the battlefield has {X} in its mana cost, X is considered to be 0.
assistant