So, Zan, the supremely useless Wonder Twin, can transform into any state of water. My question is, if he changes to say, a giant snowman, and Superman uses his heat vision on him to go from solid, to liquid, to a gas, can Zan pull himself back together? This applies to anyone who can set that useless man on fire, I'm just using Superman cause heat vision. Has anything like this ever happened?
The Wonder Twin, Zan, is a elemental hydrokinetic. He has the power to alter his physical composition into any form of liquid/water in any of the many states of fluids including steam, mist, fog, liquid or ice.
Though the Wonder Twins were thought to need to exclaim, "Wonder Twin Powers, activate" they don't actually need to describe their transformation nor their final state. They DO, however, need to make an initial contact to utilize their powers.
The revamp of the Pre-Crisis Wonder Twins in the 1995 series, Extreme Justice, made them amazingly powerful and easily able to fit into the DCU as aliens with powers beyond those of mortal men. Zan's power to become a fluid now includes any solid, vapor or gaseous form of any kind of liquid including ammonia, water or even acid.
Attacking Zan with fire or trying to change his state with heat powers while he is in his ice form does not stop him from utilizing his hydrokinetic abilities. He is still in control of his power though being damaged can reduce his effectiveness. He could also alter only parts of his body as well.