Bugbear Abomination (Storm Cast)

Brute. A melee weapon deals one extra die of its damage when the bugbear hits with it (included in the attack).
Surprise Attack. If the bugbear surprises a creature and hits it with an attack during the first round of combat, the target takes an extra 7 (2d6) damage from the attack.

Rage. The Bug Bear Abomination can use a bonus action to go into a rage. While raging it has advantage on all Strength checks and Saving Throws, adds an additional +4 to any damage and gains resistance to bludgeoning, piercing and slashing damage

Multiattack. The Bugbear abomination makes 3 attacks with its Morningstar or javelins

Greater Morningstar of Storms. Melee Weapon Attack: +9 to hit, reach 10ft., one target. Hit: 11 (2d10 +5) piercing damage + 1d6 lightening damage.

Javelin of Lightening. Melee or Ranged Weapon Attack: +9 to hit, reach 5 ft. or range 30/120 ft., one target. Hit: 9 (2d6 + 5) piercing damage in melee or 5 (1d6 + 5) piercing damage at range and then 1d6 lightening damage. When the Javelin is thrown it transforms into a bolt of lightening forming a line 5ft wide that extends out from you to a target within 120ft. Each creature in the line excluding you must make a DC 13 Dexterity Saving Throw, taking 4d6 lightening damage on a failed save, and half as much damage on a successful save. The lightening bolt turns back into a javelin when it reaches its target. Make an attack role. On a hit the target takes damage from the javelin plus 4d6 lightening damage. This part of the javelin's property can't be used until the next dawn.