Threkmóth and his folk have taken the poison-protecting potion in preparation for the assault on the Ungoledain... and possible rescue of Vaskorn.
'The honey cakes are cooling, and we are as prepared as one could imagine. Come, let us deal with these Ungoledain like the nest of hornets... or, I suppose, web of spiders that they are!'
You should talk with Threkmóth, in Skoghús, and let him know you are prepared for the journey to Kêr Bréin.