a force to be reckoned with - Someone or something that is really important and powerful.

Someone or something that is really important and powerful. You better not ignore them or they’ll ruin your day.

My mom is a force to be reckoned with. She once yelled at the neighbor’s dog for barking at me.

My math teacher is a force to be reckoned with. He can solve equations faster than a kid can eat a pizza.

My dad is a force to be reckoned with. He once threw a plate at my brother for talking back.