Clicker

Keen Hearing. The clicker has advantage on Wisdom (Perception) checks that rely on hearing. 

Echolocation. The clicker can't use its blindsight while deafened. 

Rage. If the clicker senses a target or becomes targeted by an attack, it goes into a rage and attacks the nearest target. It continues to attack the target and all other nearby targets until there are no more targets left, at which point the rage subsides.

Infectious Bite. If the clicker hits a target with a bite attack, that target must make a DC 15 Constitution saving throw or gained the poisoned condition until it is removed. If the poisoned condition is not removed before a long rest, the poison becomes a curse, making it much more difficult to remove. After finishing a second long rest, the target begins to transform into a runner, at which point the infection becomes irreversible and cannot be cured unless by means of a Wish spell or similar magic. If the creature chooses not to take a long rest, they instead gain a point of exhaustion, then gain another point of exhaustion every d4 hours until they take a long rest.

Multiattack. The clicker makes three melee attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 20 (3d8 + 6) piercing damage.

Claws. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 24 (4d8 + 6) slashing damage.