Enraged: 1/Long Rest. The Behemoth can become Enraged, causing it to gain a new set of actions, in addition to it's usual actions. While enraged, the Behemoth gains advantage on all Constitution, Dexterity and Strength checks and saving throws. In addition, it gains a +2 bonus on to-hit and damage rolls that use strength. The Behemoth also gains resistance to non-magical bludgeoning, slashing and piercing damage while enraged. This transformation lasts for 1 minute, or until the Gnasher is incapacitated. 

Multiattack: The Gnasher makes one tail attack and one bite attack, or two tail attacks. If it is Enraged, it makes one tail attack and one stomp attack. 

Tail. Melee Weapon Attack: +4 to hit (+6 while Enraged), reach 10ft, one target. Hit: 16 (4d6 + 2) bludgeoning damage. 

Bite. Melee Weapon Attack: +4 to hit (+6 while Enraged), reach 5ft, one target. Hit: 11 (2d8 + 2) piercing damage. 

Enraged Actions: These attack options are available only while the Gnasher is Enraged. 

Stomp. Melee weapon attack: +6 to hit, reach 5ft, sphere. Hit: 13 (2d8+4)bludgeoning damage, and the target must make a DC 12 Strength saving throw, or be knocked prone.