It is very important to have that rested buff happening for stamina regen as so many have pointed out. Always a good idea to have a portal shack near a boss fight. I always have a master portal in my HQ bedchamber, which is my go to set spawn point. I will set that portal designation to the nearby boss portal eg; "Moder Dock" when I am ready to undertake a boss fight. At the foot of my bed is a chest with a second set of gear, food, potions, ammo, so recovering my tombstone right away is optional. I is a good idea when fighting mobs like Bonemass & Moder, where the environment almost always keeps that wet and or cold debuff on, to make a nearby sheltered campfire or two. I had 3 covered fires going up against Bonemass, that were tucked in behind some logs tangled with trees, on the lee side of a hill facing away from Bonemass' altar.