Scorestreak

The Scorestreak system is a multiplayer mechanic introduced in Call of Duty: Black Ops II, replacing Killstreaks and Strike Chains. In this system, rewards are earned based on the amount of score one earns in a single life.

Overview
In previous Call of Duty games, players earned killstreaks by getting a certain number of kills in a single life. Modern Warfare 3 introduced Point Streaks where players earn points by not just getting kills, but also by completing objectives, i.e. capturing Domination flags and planting S&D bombs, and by destroying enemy killstreak rewards, i.e. UAVs and Sentry Guns; these points in turn give rewards. However in Call of Duty: Black Ops II, players now earn rewards for earning a certain amount of score  in a single life. This means actions like kills, captures, completing objectives, shooting down enemy air support, assists, and assists with certain scorestreaks count towards the earning of new scorestreak rewards. Like in previous Call of Duty games, the player's streak will reset upon death.

The Player's Scorestreak rewards can be obtained multiple times in one life, but only if the player uses his/her scorestreak prior to receiving the same scorestreak again. For example, if the player earns the Swarm scorestreak, chooses to save it, and they earn the Swarm again, the first Swarm will be lost, being replaced by the second Swarm received by the player.

Contrary to most previous games, dying does not impede progression by called in streaks. While any points gained are lost upon death, the player may still receive points through streaks (most of them except UAV, Counter-UAV, orbital VSAT and EMP systems assists) called in before being killed or by calling in streaks that they have saved up. As long as points are awarded after death, it doesn't matter when a scorestreak has been called in nor when it has been earned.

Using the perk Hardline, the score towards the player's scorestreak is increased by 25% meaning this perk is extremely beneficial for obtaining the higher rewards. For example, if one was trying to receive a Swarm and was using Hardline, he would only require a 1585 scorestreak rather than 1900. This equates to 3 fewer kills in Team Deathmatch.

Trivia

 * In Champions League, the UAV, Hunter Killer, Care Package, Counter-UAV, Guardian, and Orbital VSAT are disabled.