Dragonglass, the all-consuming Game of Thrones weapon, can find a bit confusing.
It could immediately turn the White Walkers into ash however it is what generated the Night King and ceased Benjen Stark from turning undead? Yeah, it’s a lot.  

The obsidian-like glass will be critical against the Army of the Dead more than dragon flame. Viserion’s rapid passing accompanied by the Night King reanimating him as an ice dragon proves that as dear as they are, Dany’s children may not make it into the end.
Dragonglass has existed for centuries. For a instant in Season 1, it was mentioned in the context of this series but didn’t make its debut until Season 2. From now Season it’s worth has improved.  
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