Ninja returns as a Tier 3 perk in Black Ops. It is roughly equivalent to the Dead Silence perk from past Call of Duty games and shares effects with SitRep Pro in Modern Warfare 2.
Ninja reduces all player noise by 75%. Its pro version completely silences the player and doubles the volume of enemy sounds. Teammates without Ninja will be heard normally by the player.
Unlike in past Call of Duty games, Ninja Pro is not limited to footsteps alone. Ninja Pro silences falling, mantling, weapon switches, equipment deployment, and more. It also does more than double enemy footsteps; callouts, reloading, and equipment deployment all have increased volume. It is useful to know the language of your team to distinguish friend from foe.
The November 18th patch balances audio levels making player noises much easier to detect. This makes Ninja and Ninja Pro much more useful. However, even with Ninja Pro, enemies do not make nearly as much movement noise as they do in Call of Duty: Modern Warfare 2. The volume of footsteps varies widely depending on the ground surface; on some surfaces footsteps are nearly silent. Additionally, while sprinting on some surfaces footsteps seem to make noise only every third or fourth step, again minimizing the usefulness of this perk.
Ninja Pro seems to let you pick up on enemy footsteps from slightly further away but not necessarily louder. Having a line of sight definitely lets you hear the footsteps easier than if you are around a corner. Most of the time you can't even hear the footsteps until the enemy player hits the corner and then it's too late.
Even with Ninja Pro, players will hear themselves mantling. This may be a bug and it's unclear if enemies can also hear the noise.
- Silenced Kills – Get 150 kills using the Suppressor attachment.
- Back Stabs – Get 5 Backstabber Medals.
- Plants – Plant the bomb 10 times in Demolition, Sabotage, or Search & Destroy.