Fight tooth and nail
Definition 1 of 1
Pro Tip 1/3Visual Imagery
The phrase paints a vivid picture of a person using their teeth and nails, suggesting intense effort or aggression. 
During the debate, he fought tooth and nail to defend his point.
Pro Tip 2/3Extreme Measures
It implies doing everything possible, sparing no effort, to achieve a goal, almost like a last resort. 
To protect her family, she would fight tooth and nail.
Pro Tip 3/3Intensity
The phrase reflects a very high level of determination, beyond ordinary effort. 
He fought tooth and nail to overcome the obstacles in his way.