Urthok, Chief Druid of Melora

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

Heart of Melora. Urthok has advantage on saving throws against being charmed, frightened, paralyzed, poisoned, stunned, or put to sleep.

Surprise Attack. If Urthok 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.

Guardian of the Glade. Urthok is immune to negative effects from Melora's Mind Bloom. 

Multiattack. The bugbear makes two melee attacks with his staff. He can replace both attacks with a use of Spellcasting. 

Quarterstaff. Melee Weapon Attack: +5 to hit, reach 10 ft., one target. Hit: 12 (2d8 + 3) bludgeoning damage.

Spellcasting. Urthok casts one of the following spells, using Wisdom as the spellcasting ability (spell save DC 17):

At will: beast sense, entangle, speak with animals

3/day each: animal messenger, dominate beast, faerie fire, tree stride

1/day each: commune with nature (as an action), mass cure wounds

Wild Shape (2/Day). Urthok magically transforms into a Beast or an Elemental with a challenge rating of 6 or less and can remain in that form for up to 9 hours. Urthok can choose whether its equipment falls to the ground, melds with its new form, or is worn by the new form. Urthok reverts to its true form if it dies or falls unconscious. Urthok can revert to its true form using a bonus action.

While in a new form, Urthok's stat block is replaced by the stat block of that form.