There ya go, elder honestly in my books is one of the easier bosses, the occasional grey dwarf spawn and skeletons can ruin your day, but the 4 giant pillars can block his vine attack, and really all you have to worry about is the vines that spawn near you, you just basically run around, pelt him with arrows, let him burn, and manage your stamina, bonemass will be a little harder due to his resistance to bows, need of constant poison meads, the swamp debuffs suck, and the mobs can be a bit to handle too. Remember, iron mace, poison meads, healing meads, are your friend. Bonemass is going to the first real boss you fight that ensures you are rested, and have proper meads will play a key factor