Bellowing Bear

Thundering Presence. At the start of every turn every creature within a 30ft radius centered on the Bellowing Bear must make a Constitution saving throw(DC 18) or take 3d4 lightning damage.

The Vrestrom's Calling. When the Bellowing Bear drops to 0 hit points it calls upon the power of The Volibear and sends out a shockwave of thunder. All creatures within a 15ft radius must make a Dexterity saving throw(DC 18) or be knocked prone and take 3d8 lightning damage.

Multiattack. The Bellowing bear can make three melee attacks: two with it's claw's and one with its bite.

Claw. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 9 2d8+8 slashing damage. 

Bite. Melee Weapon Attack: +10 to hit, range 5 ft., one target. Hit: 10 3d6+5 piercing damage plus 1d12 lightning damage

Aggressive. As a bonus action, the creature can move up to its speed toward a hostile creature it can see

The Bellowing Bear can take 1 legendary action per turn. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The Bellowing Bear regains spent legendary actions at the start of its turn.

Consume Rot (Costs 1 Action) The Bellowing Bear consumes its own flesh and heals 2d8 hit points, if the Bellowing Bear takes fire or cold damage before it uses this feature it only heals 1d8 hit points.