Enrage: At 100hp the beast enrages. It's muscles become as hard as iron and its horns begin to shine with barely contained energy. The creatures AC increases to 18. In addition all of its melee attacks deal an additional 1d6 bludgeoning damage. It also gains access to new attacks. Bloodied: At 50hp the beast goes all out in a last ditch attempt to survive. The beast unleashes shocks of energy all around it from its body. Any creature that gets within 5ft of the creature takes 2d4 +3 lightning damage. In addition it gains access to additional attacks. Grappler: If this creature successfully lands an attack on a creature, it can grapple that creature as a bonus action.
Fist: +9 to hit, 2d6+7 bludgeoning damage. Static Discharge: The bear discharges lightning in a 20ft cone in front of it. Any creatures caught in the discharge must make a DC20 CON save or take 6d8+12 lightning damage on a failed save or half as much on a successful one. Lighting Beam: The bear exhales a 5ft wide 200ft long lighting beam. Any creatures caught in the beam must make a DC22 CON saving throw taking 10d8+18 lightning damage on a failed save or half as much on a successful one.
Jungles, Forests, or anywhere with a large concentration of things to swing on.