2* seeker soldiers are huge health sponges and they deal great amount of damage...

According to the Fandom wiki, the mistlands boss has ("only") 12500 health. 2* seeker soldiers have 4500...

Never seen a high rank gjall myself, but I often carry fire resistance wine since I like to head out with root harnesk. Not sure which I'd prefer since I don't know the other. But gjall don't have physical resistance as soldiers do.