Sneak attacks are attempted automatically when you attack unsuspecting Conservatives with a knife. You add your stealth to the attack roll, and the victim will defend with their Wisdom instead of their dodge. If the attack is successful, you'll stab the target in the head or body and will usually kill the target instantly. This attack does not cause any alarm if it is successful. This is best used against Important Conservatives, due to the fact that it tends to be an instant kill and can prevent you from succumbing to ARCH CONSERVATIVE BRAINWASHING!!!
If there are other Conservatives present who are not immediately taken out in the same fashion, your attack is unsuccessful, or the target's armor causes them to survive the attack, the jig is up and the site alarm will be raised. Multiple Liberals can attempt sneak attacks in order to silently take down larger groups of enemies, as long as nothing goes wrong; one failed attack and the rest of your party will have to fall back on traditional knife fighting.
Note that while killing Conservatives in this way may not cause immediate alarm, leaving a trail of bodies is still highly suspicious; you will not have long before the Conservatives figure out something is going horribly wrong, even if they have yet to identify you as the perpetrator. And while this new attack makes knives a very powerful infiltration weapon, sneak attacks can't be used in sieges or any other circumstance where the Conservatives are already alarmed.