Shapechanger. The gnoll can use its action to polymorph into a hyena or back to its true form. Its statistics change to match the hyena's in this form. Any equipment it is wearing or carrying isn’t transformed. It reverts to its true form if it dies.

Hyena Form

Pack Tactics. The hyena has advantage on an attack roll against a creature if at least one of the hyena's allies is within 5 feet of the creature and the ally isn't incapacitated.

Gnoll Form

Rampage. When the gnoll reduces a creature to 0 hit points with a melee attack on its turn, the gnoll can take a bonus action to move up to half its speed and make a bite attack.

Hyena Form

Bite. Melee Weapon Attack: +2 to hit, reach 5 ft., one target. Hit: 3 (1d6) piercing damage.

Gnoll Form

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one creature. Hit: 4 (1d4 + 2) piercing damage.

Spear. Melee or Ranged Weapon Attack: +4 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 5 (1d6 + 2) piercing damage, or 6 (1d8 + 2) piercing damage if used with two hands to make a melee attack.

Longbow. Ranged Weapon Attack: +3 to hit, range 150/600 ft., one target. Hit: 5 (1d8 + 1) piercing damage.