u/Kazzualty

Hey everyone! Returning player after many years away and needed some clarification. I played at launch for a while and had a warrior at lvl 80 with the finished main story. I had purchased Heart of Thorns expansion before I stopped playing but I never actually started that story quest line before leaving. I know that people recommend doing HP trains to farm hero points for the elite specializations because I’ve heard each hero point challenge gives more hero points in the expansion zones, or is that only for the later expansions? Is it recommended/required that I unlock all the fast travel waypoints first in those new zones before joining a train or no? Just looking for advice. Thanks all!!