Ice dragon? Good luck

Okay how in the hell do you kill an Ice Dragon? I mean Lannisters tried to kill a normal dragon and failed horribly.... Jon snow can barely kill white walkers, and now there is a white walker dragon... Good freaking luck with that one. They are going to have to make valyrian steel giant spear to shoot it down... I dont think dragon glass is going to be strong enough... So where is the spear going to be made, and how are they going to get the materials... So many questions and never enough answers! It funny too because Bran already know how this one ends hahaha