3 headed dinosaur

Construct. The beast does not need to breathe, drink nor eat

Pounce. If the beast moves at least 30 feet straight toward a creature and then hits it with a claw attack on the same turn, that target must succeed on a DC 13 Strength saving throw or be knocked prone. If the target is prone, the beast can make one bite attack against it as a bonus action.

Multiple Heads. The beast has three heads. While it has more than one head, the beast has advantage on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious.

Whenever the beast takes a third of its HP or more damage in a single turn, one of its heads dies. If all its heads die, the hydra dies.

Reactive Heads. For each head the hydra has beyond one, it gets an extra reaction that can be used only for opportunity attacks.

Wakeful. While the beast sleeps, at least one of its heads is awake.

Multiattack. The beast makes as many bite attacks as it has heads.

Bite. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 11 (1d10 + 6) piercing damage.

Claw. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 10 (1d8 + 6) slashing damage.