Bjorn spiritcaller
Bjorn spiritcaller has 1,500 health.
It takes extra damage from fire; it resists blunt, pierce and frost; spirit does nothing to it at all. Slash lands at full damage, so that is what to bring.
Its hardest hit is bite at 100 pierce, out of 6 attacks.
Of everything craftable, 
Lightning Strike, 
Thunderblood Greatsword and 
Frostfire Greatsword put the most damage through what it resists.
It can be tamed with 
Blueberries.
Bjorn spiritcaller is a bear summoned to fight on your side by the 
Spirit Caller, not something that spawns in the world. At 1,500 health it is three times as durable as a wild 
Bear and the toughest summon the staff produces. It keeps the bear's defenses, resisting blunt, pierce and frost, immune to spirit damage and weak to fire, and it runs at 7 from a walking speed of 1.5. It counts as a tamed creature, eats Blueberries, and leaves no drops.
Resistant to blunt, pierce and frost, immune to spirit, and weak only to fire. In the Deep North, where almost everything hitting you is blunt or frost, that means the bear actually holds a line rather than dying to the first sweep. It takes blueberries. Keep it away from anything burning.
With devcommands enabled, this spawns Bjorn spiritcaller in front of you. The third number is the level: 3 spawns a 2-star.
Creature ID: Bjorn_spiritcaller · all console commands and IDs