If you find yourself still emotionally destroyed about the extremely untimely dragon death in last Sunday's Game of Thrones, you are certainly not alone. When the Night King threw that ice spear like an Olympic gold medalist, successfully killing Viserion, it was unbelievably tough to stomach. Things got even more tragic when the episode ended with the Night King turning Viserion into a wight (or a white walker depending on who you ask). Game of Thrones officially has ice dragons and now there is set to be a battle between Dany's living, fire-breathing babies and an undead ice dragon. So, can fire kill ice dragons on Game of Thrones?
This is a very complicated subject because there one has to first determine the difference between White Walkers and wights. White Walkers are the dudes like the Night King and his associates, who don't look to be actively decaying and can walk through fire and not die. Wights are the army of decaying zombies that can be killed by fire, dragonglass or Valyrian steel. This same methodology wouldn't work for the Night King and the other White Walkers — which can only be killed via dragonglass or Valyrian steel.
So, since you now know the difference between wights and White Walkers, it is important to distinguish what exactly Viserion has become. When the Wight army dragged Viserion out of the frozen lake with those big ol' chains, the Night King strolled forward and with one touch (this is important), the dragon's eyes flicked open to reveal the familiar bright, icy blue eyes. So, because the Night King went to the trouble of touching Viserion to change him, my bet is on the fact that he is a White Walker now and not a wight. When the Night King rose the dead in Hardhome (the "come at me bro" moment), he rose the dead without touching anyone. So, a touch by the Night King may mean something extra special.
If I am correct that Viserion is now a White Walker and not a wight, then he can not be killed by fire. This flying beast can only be killed with dragonglass or Valyrian steel, which won't be easy to accomplish. As fans saw in Sunday's episode, White Walkers even survived dragon fire, which the Wights did not. I am thinking the White Walkers purposely made Viserion a White Walker because this means that his brother Drogon and Rhaegal can't kill him with their fire. This is good, because we won't have to see them kill their own brother, but it is bad because this means the White Walker army is essentially indestructible now.
So, while we are certainly in for some serious battling between the army of the dead and Dany/Jon's troops, the good guys are woefully unprepared —even with Drogon and Rhaegal on their side.