Is the quest called Lands of Always Winter?

Then you have to find a White Walker, it will have a purple name.

Usually he roams to the west of the free folk.

But be warned, The White Walker has a large amount of wights and giants which are very deadly! You'll need to be high level with upgraded armour and Valyrian/Obsidian weapons. If you own King's Landing you can produce wildfire jars as a throwing weapons which works well on groups of them. Only bring high level companions with weapons able to help kill them otherwise troops will just be slaughtered.

Just a tip, pick Jon Snow as Commander whilst planning your attack against them, since he is really OP and he has a valyrian sword

alright thank you!
I am level 9 and have about 60 men and only dragonglass arrowheads and jon snow already left me because i traveled to far south. so i guess the quest will have to wait for a long time :D:summerghost:

This quest is a kind of no win no matter what. you don't get enough time to get enough renoun to be able to get the said weaponsmith to deal with you. All I do is go find them on the open tundra north west of Thenn...ish. when you meet them you face a choice leave or fight. if you fight you will get mashed but fatality's are about 25% of your force. I've tried various ways including all captains with fire arrows with no real effect. you are going to take a hit to moral and renoun. My best result was fighting till everyone has dropped or run and hope not to be captured. if your troops drag you away you can then leave and you don't get the moral renoun loss. Then head back to castle black and report.

The quest can be completed whenever, there is no time limit.

yes there's no time limit, but once jon snow is in party he starts thretenig to leave as soon as you go south and head to qohor to try and get the valarian weapon. Especialy since He won't deal with you and just laughs.