Bugbear Spellrager

Brute. A melee weapon deals one extra die of its damage when the bugbear hits with it (included in the attack).

Magic Resistance. The Bugbear Spellrager has advantage on saving throws against spells and other magical effects.

Brutal Defense. Any creature that comes within reach of the bugbear provokes an attack of opportunity. Any creature that attempts to leave the bugbear's reach provokes an attack of opportunity.

Bloodlust. When the bugbear reaches half health, it goes into a reckless frenzy. All of its attacks have advantage. All attacks have advantage on it. It gains resistance to slashing, piercing, and bludgeoning damage. It critical hits on a 19 and 20.

Innate Spellcasting. The Bugbear's innate spellcasting ability is Wisdom (spell save DC 13, +5 to hit with spell attacks). The Bugbear can innately cast the following spells, requiring no components.

• At will: firebolt, message
• 2/day: burning hands, charm person, detect thoughts, sleep
• 1/day: fireball, lightning bolt

Multiattack. The Spellrager makes two attacks 

Maul. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 13 (3d6 + 3) piercing damage.

Javelin. Melee or Ranged Weapon Attack: +4 to hit, reach 5 ft. or range 30/120 ft., one target. Hit: 9 (2d6 + 2) piercing damage in melee or 5 (1d6 + 2) piercing damage at range.