Killstreaks are rewards or bonuses that are gained by killing a certain number of enemies in a row without dying. The Hardline Perk will lower the numbers below by 1 kill. It has been expanded from Call of Duty 4 and World at War as you can customize your killstreak rewards to something suitable for your experience and your liking. It is a maximum of 3. You do have to unlock them as you go so not all are available right away.
Killstreaks are stackable. Meaning you don't lose the previous reward when you get the next. For example... if you have a UAV, you wouldn't lose that UAV when you gain a Care Package or something else. They can't be used as you please though either. You have to use the most recent one first. You don't lose them if you die either.
3 Kills
UAV
This deploys a UAV (unmanned aerial vehicle) that shows the enemies on the radar as dots. The UAV can be shot down by the enemy.
This can be blocked with the Cold-Blooded perk.
4 Kills
Care Package
After you throw the red signal flare, the Care Package will be airdropped into the battlefield. This can be picked by anyone, even the enemy.
The package contains either a random killstreak or ammo. The killstreak can be anything from the UAV to the EMP, regardless what killstreak rewards you have chosen.
% Chance of What Will Come:
14.78% - UAV
14.78% - Ammo
13.04% - Counter-UAV
10.43% - Sentry Gun
10.43% - Predator Missile
9.57% - Precision Airstrike
6.09% - Harrier Airstrike
6.09% - Attack Helicopter
4.35% - Pave Low
4.35% - Stealth Bomber
2.61% - Chopper Gunner
2.61% - AC-130
0.87% - EMP
Counter-UAV
This disables the enemy radar for a short period of time, even if they don't have a UAV in the air.
5 Kills
Sentry Gun
Airdrops a placeable XM312 Sentry Gun that will automatically fire at enemies. It can be destroyed by normal means, or temporarily disabled with Flashbangs and Stun Grenades. The cold blooded perk will make you invisible to them making destroying them very easy by running right up to them and using your knife.
The Sentry Gun has about a 120 to 150 degree turn on its turret and can pitch up and down. You can move the Sentry Gun around even after you've deployed it, but it won't fire until it's placed. They are most effective when placed in high places.
Predator Missile
This allows you to remote control a Predator missile. After opening the laptop, you have approximately 5 seconds to control the missile to your target, as it goes down. You can also give the missile a boost to make it go down faster by pulling the normal "shoot" trigger. The cold blooded perk will remove the red box from your name when enemies are using this killstreak reward.
You are vulnerable while using the Predator missile, but if you get killed, you can still continue to control it.
6 Kills
Precision Airstrike
This is much like the Airstrike from Call of Duty 4, but this time you can control the direction of the Airstrike for more accurate kills. You should have a teammate activate a UAV for you as you will be able to utilize their location for better placement.
7 Kills
Harrier Strike
Airstrike with a hovering Harrier. After dropping its bombs, the Harrier will guard the area for a short period of time. The hovering Harrier is quite effective as you have to be very quick with your launcher to take it down. The cold blooded perk will make you invisible to the Harrier.
Attack Helicopter
Deploys a helicopter to the battlefield like in Call of Duty 4. It will circle the map and automatically attack the enemies for a few minutes and leave. It can be destroyed with guns and missiles. The cold blooded perk will make you invisible to the Attack Helicopter
All the enemies that it kills are added to your kill count.
8 Kills
Emergency Airdrop
Airdrops 4 random killstreaks or ammo. This is the same as the Care Package, but x4.
% Chance of what you will get:
Ammo: 12.0%
UAV: 12.0%
Counter-UAV: 16.0%
Sentry Gun: 16.0%
Predator Missile: 14.0%
Precision Airstrike: 10.0%
Harrier: 5.0%
Attack Helicopter: 5.0%
Pave Low: 3.0%
Stealth Bomber: 3.0%
Chopper Gunner: 2.0%
AC-130: 2.0%
9 Kills
Pave Low
This deploys a heavily armored Attack Helicopter (Sikorsky MH-53 Pave Low) to the map for maximum carnage. As with the Attack Helicopter, all the kills are added to your kill count. Once again, the cold blooded perk will keep you invisible.
Stealth Bomber
Calls in a Stealth Bomber (B-2 Spirit) to carpet bomb the selected area. You can also control the direction, just like with the Precision Airstrike.
The airstrike doesn't show on enemy radar.
11 Kills
Chopper Gunner
Be the gunner of an attack helicopter. The chopper will fly around the map and you can remotely control the 25mm gun with your laptop. The cold blooded perk will remove the big red box around your player for any enemies that gain control of a Chopper Gunner.
AC-130
After the AC-130 Gunship is deployed via laptop, it will enter the map. You control it remotely for 30 seconds and you can use the 25mm, 45mm and 105mm guns to shoot at enemies. You are vulnerable while controlling the AC-130, but if you get killed while using it, you can still continue. The cold blooded perk will remove the big red box around your player for any enemies that gain control of an AC-130.
Note: The AC-130 can be shot down by the enemy, but it does have flares as countermeasures.
15 Kills
EMP
Electromagnetic pulse or EMP for short. Temporarily disables enemy electronics like the Thermal Scope, Red Dot Sight, etc.
The EMP also stops the enemy from using killsreaks and at the same time drops down any helicopters and aircrafts that are in the air.
25 Kills
Tactical Nuke
Gives you and your team an instant win regardless of current score. The Tactical Nuke ends the match with a bang by killing everyone on the map.
% for care package and emergency air drop were gathered from
Modern Warfare 24/7
Modern Warfare 2 Kill Streak Rewards
Linear Mode
