Does anyone have any ideas for an evil underground operation?

My character is a villain in secret, and she collaborates with other heinous criminals. There will be times throughout the book when she undertakes an operation for/with them in order to weaken or defeat the heroes. Does anyone have any ideas as to what she could do?

Maybe having the villain try to attack the hero's loved ones? She could attack cities too in order to try to draw out the heroes? (Not sure if this helped, but good luck writing :)

Thank you! I will be sure to use this in my story.