Hardline

Hardline is a Tier Two perk available in Call of Duty: Modern Warfare 2 and Call of Duty: Modern Warfare 3, and as a Tier One perk featured in Call of Duty: Black Ops, Call of Duty: Black Ops II, and Call of Duty: Black Ops: Declassified and appears as an Elite perk in Call of Duty: Ghosts.

Call of Duty: Modern Warfare 2
In Call of Duty: Modern Warfare 2, it allows the player to gain their killstreak rewards with 1 less kill. For instance, if the player had UAV, Care Package and Predator Missile as killstreak rewards, rather than needing 3/ 4/ 5 kills respectively, they would only need 2/ 3/ 4 kills.

Hardline Pro is unlocked after obtaining 40 killstreak rewards (not getting at least a two kill streak 40 times, as some may think). The easiest way to do this is set the player's killstreak rewards to require 3/ 4/ 5 kills. Hardline Pro reduces the number of deaths needed for a deathstreak by 1.

"Preemptive Strike" Title is unlocked by completing Hardline Pro I Challenge. The "Close Support" title is unlocked by completing Hardline Pro VI Challenge along with the perk emblem.

Call of Duty: Black Ops
Hardline returns as a Tier 1 perk in Call of Duty: Black Ops.

Overview
Hardline reduces all killstreak requirements by one. Its Pro version allows the player to "re-roll" the Care Package killstreak by double-tapping the action button for console versions and the reload key for PC versions, which will change its contents randomly. A Care Package can only be re-rolled once, and will always change its content.

Originally, the SAM Turret, Sentry Gun, and Valkyrie Rockets killstreaks crates could also be re-rolled; however, the December 14, 2010 patch limited Hardline Pro's functionality to the Care Package alone.

Below is a table showing the default Care Package probabilities compared to the re-roll probabilities. As can be seen, re-rolling favors middle killstreaks much more than Care Packages, while higher killstreaks are almost unchanged.

Hardline gives the player model medium body armor in the form of Kevlar vest, a helmet on some models and a radio device located on the character's shoulder. However, this particular device is only aesthetic; all players have a radio to call in Killstreaks.

Pro Challenges

 * Share Packages – Share 10 Killstreak reward crates with teammates.
 * Multiple Killstreaks – Earn 7 killstreaks in one match while using Hardline.
 * Killstreak – Get 7 kills without dying in one life.

Call of Duty: Modern Warfare 3
Hardline returns as a Tier 2 perk in Call of Duty: Modern Warfare 3.

Overview
Hardline makes each pointstreak require 1 less point. This applies to all three strike packages and all of the point streak rewards, even the M.O.A.B.

Hardline Pro is unlocked by obtaining 80 point streak rewards using Hardline. The Pro version has two effects; it reduces the number of deaths required for a deathstreak by 1, and it also adds 1 point to a user's point streak for every 2 assists earned. Hardline Pro can be easily unlocked when using the Specialist Strike package, as only a single point is needed to earn the first perk.

Call of Duty: Black Ops Declassified
"Killstreaks require 1 less kill."

- In-game description.

Hardline returns as a Tier 1 perk in Call of Duty: Black Ops Declassified. It retains its effect from Black Ops, making killstreaks require one less kill to obtain.

Call of Duty: Black Ops II
"Earn Scorestreaks faster."

- Create-A-Class Description.

Hardline returns in Call of Duty: Black Ops II. Hardline increases score earned towards Scorestreak by 20% (not counting UAV, Counter-UAV, Orbital VSAT, or EMP assists). This equates to Scorestreaks requiring 16.7% less score to earn, equivalent to approximately 1-2 less kills to earn a Scorestreak, and even 3 less kills to earn a Swarm.

Call of Duty: Ghosts
Hardline returns in Call of Duty: Ghosts as an Elite perk. It requires two perk points to use and it is unlocked at level 20. Pointstreaks require one less point to obtain, and every two assists counts as a kill towards their killstreak.

Call of Duty: Modern Warfare 2

 * The perk is named differently in different languages of the game: in the French version it is "Determination", in Polish it is "Uncompromising" and in Russian the base perk is "Implacability" while the Pro version is "Hard Game Pro".

Call of Duty: Black Ops

 * In Call of Duty: Black Ops, one cannot re-roll booby trapped Care Packages, making it easier to tell if one has been hacked.
 * The perk is named differently in other languages: in the French version it is "Implacable", in the Polish version it is "Soldier" and in Russian it is "Lucky".

Call of Duty: Modern Warfare 3

 * Obtaining Hardline via the Specialist Strike Package counts towards Hardline Pro.