Bovine Shrieker

Aggressive. The shrieker can charge at a creature within 40 feet of it. When it does so, it uses its bonus action to Dash. This movement can be used to provoke Goring Rush.

Goring Rush. If the shrieker moves at least 10 ft toward its target and then hits with the gore attack, the attack deals an additional 7 (2d6) bludgeoning damage and the target must succeed on a DC15 Strength saving throw or be pushed ten feet back and knocked prone.

Wordless Screaming. The shrieker’s unnatural, human-like mouth is permanently fixed open, emitting a high pitched screaming noise. Any creature not a part of the legion that starts its turn within 30 feet of the shrieker must succeed on a DC15 Constitution saving throw or be cursed for one minute. While cursed in this way, the creature has disadvantage on attacks and saving throws made while within 30 ft of a shrieker. An affected creature can repeat the save at the end of each of its turns, ending the curse on a successful save. Ending the curse, either by saving or by waiting out the effect, renders the target immune to this curse from all shriekers for 24 hours.

Multiattack. The shrieker makes two gore attacks on its turn

Gore. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 14 (3d6+4) piercing damage.

Reactionary Bite. In response to taking melee damage, the shrieker opens its actual mouth by twisting its entire neck open and bites. It continues shrieking the entire time.

Bite. Melee Weapon Attack. +6 to hit, reach 5 ft. Hit: 15 (2d10+4) piercing damage, and the target must succeed on a DC15 Constitution saving throw or be cursed with Metamorphosis. See the Metamorphosis table for details.