Is there a martial art that specializes in breaking the neck?

There is no specific style that only does neck breaking only techniques from various styles

Breaking the neck is not an easy task, the more likely out come is you will royally screw the persons neck up.
There is only one technique I have learned that has a chance of breaking the neck and that is because it does not rely on twisting action but on leverage, utilizing the mechanics of the opponents head and neck to help the effect, that technique was from kyoshi-jitsu and is in several advance kata.

Not really. Some martial arts like Catch Wrestling (Catch-As-Catch-Can) and some Silat systems are known for their neck cranks and wrenches, but no system I'm aware of is built around that, and for good reason. Not only is it VERY hard to actually, physically break the neck (most cervical fractures in fighting come from being dropped/thrown on top of the head, no easy task itself), but in order to get such an opportunity, you have to get past nearly every other offensive and defensive tool the opponent has: kicks, punches, knees, grabs, etc.

You know like alot of Black belts in the Leth of spech hawks or traus nips i know sech will see no block in M Law sud