Martyrdom

Martyrdom is a Tier 3 perk in Call of Duty 4: Modern Warfare and Call of Duty: World at War (and a Deathstreak in Call of Duty: Modern Warfare 2) that gives the player the ability to drop a live fragmentation grenade upon death.

Overview
A Martyrdom grenade's fuse is 2.5 seconds (as opposed to the 5 second fuse of a non-Martyrdom grenade, and a grenade that is picked up with the Toss Back Perk, which is 3 seconds). The grenade cannot be considered "cooked" since a player would have to pick it up. A player with the Martyrdom perk who is killed cooking a grenade will drop both the grenade that was held and the Martyrdom grenade.

An interesting fact is that enemies can be damaged by the grenade while it is falling, on rare occasions resulting in direct impact kills. During single player, some enemies will perform a variation of this perk. They drop to the ground and actively pull the pin from a grenade before slumping over dead.

Call of Duty 4: Modern Warfare
"Drop a live grenade when killed."

- Perk description

The perk is most effective in close quarters; where enemies are less able to escape its blast.

Problems about this perk
Some servers on the PC version ban the use of Martyrdom, either for it being considered cheap, or that it can become annoying if many/all of the players on a server have it, though many also argue that the inclusion of this perk is simply part of the game and can be easily avoided by more experienced players.

It is also frowned upon to use in Hardcore Team Deathmatch and Hardcore Search and Destroy, given that the dropped grenade can also kill teammates (thus it is far rarer on those modes). However, it can still be useful against enemy players because they won't be expecting martyrdom and there wont be any grenade indicators so players still sometimes use the perk in those modes, and due to decreased player health, the perk becomes much more effective if teamkills can be avoided.

Many players despise Martyrdom as it is considered to be cheap way to earn kills since there is usually absolutely no skill required, and one is basically rewarded for dying. However, Martyrdom can also be used tactically, such as a with an SMG. Some players even use Martyrdom as a suicide bomb by running into an enclosed area with enemies and allowing themselves to be killed in hopes of taking down one or more enemies.

Call of Duty: World at War
Martyrdom reappears in Call of Duty: World at War just as it did in Call of Duty 4: Modern Warfare. There is no significant difference between the two perks from the two games, as both grenade times are 2.5 seconds. The only possible difference would be that the grenade indicator for Call of Duty: World at War dims down when players are further away from a live grenade (Treyarch developers have changed the effect of grenades).

Thus, the dimmer the indicator, the less damage taken. This is not true in Call of Duty 4: Modern Warfare as even if players are at the minimum range of the Martyrdom, they would still be killed. Due to this fact, it is much easier to escape from Martyrdom in Call of Duty: World at War, as the player that killed the Martyrdom user will usually end up backpedaling.

Call of Duty: Modern Warfare 2
Martyrdom returns as a Deathstreak in Call of Duty: Modern Warfare 2. It requires four consecutive deaths before it can be used (three if using Hardline Pro), so it is seen far less frequently than it was in previous games. It is also weaker, as the grenade fuse time has been increased to that of an uncooked fragmentation grenade.

The decrease in effectiveness has also been amplified by the reduction in damage and range to the fragmentation grenades in Modern Warfare 2.

General

 * If Martyrdom kills an enemy after respawning it will count towards a new kill streak.
 * A player without Martyrdom can throw back a grenade dropped by Martyrdom to achieve challenges requiring the use of Martyrdom.
 * Martyrdom is especially effective in hardcore ricochet game types. The user's teammates will be unaffected, and so will the user, as he or she is already dead.
 * In Call of Duty: Modern Warfare 2, Call of Duty: World at War and Call of Duty: Black Ops singleplayer campaigns, badly wounded enemies who have been shot near a wall or are leaning against something will drop a live grenade after they bleed out and die.
 * In Call of Duty: Modern Warfare and Call of Duty: World at War, Martyrdom was used by many people, but as the frag power was decreased and Martyrdom was turned into a deathstreak in Modern Warfare 2, it has become very uncommon.
 * In World at War, a Japanese soldier can be seen pulling the pin on a grenade, then hitting himself with it. He pulls the pin just when the player enters the bunker, so there is a probability that he may take the player with him too.
 * A lot of players pronounce it "Martydom", which is incorrect.
 * The emblem of Martyrdom in Call of Duty: Modern Warfare and Call of Duty: World at War is green but in Call of Duty: Modern Warfare 2 it is red.

Call of Duty 4: Modern Warfare

 * In the Call of Duty 4: Modern Warfare multiplayer beta, the Martyrdom grenade fuse was 5 seconds; this proved problematic as players were able to easily pick up the Martyrdom grenade and throw it away.
 * As seen in game menu source files, the Call of Duty 4 version of Martyrdom was originally a Tier 2 perk.

Call of Duty: World at War

 * In the Single Player campaign, if the player injures an enemy, and they go down, they are capable of several things, including Last Stand. Some enemies will actually pull the pin on a grenade and blow themselves up, and hope the player gets killed too. This tactic is dangerous to players who run and gun, for they may not be aware of a lone dying German caught in their spray and may kill the player if in close proximity, even on Recruit.

Call of Duty: Modern Warfare 2

 * In Call of Duty: Modern Warfare 2, it is possible to use both the Last Stand perk and Martyrdom simultaneously. This is unwise if the player does not have Last Stand Pro; when Martyrdom is active, a player will enter Last Stand mode and simultaneously drop a grenade, killing the player within seconds and thereby depriving them of the benefits of Last Stand. However, with Last Stand Pro, players can throw the grenade away, both saving themselves and giving them a free grenade.
 * In Call of Duty: Modern Warfare 2, if you kill an enemy with this deathstreak you will get the title Martyr and a martyrdom emblem. It is also possible to get this kill by throwing away an enemy Martrydom grenade if possible.
 * In Call of Duty: Modern Warfare 2, on Hardcore Ricochet: HQ Pro, due to the nature of martyrdom grenades fuse timer and HQ Pro's instant respawn timer, it is possible for the player to respawn before the grenade goes off. If the grenade explodes next to a friendly after respawning, the player will be killed by the friendly fire ricochet and hence drop another martyrdom grenade (assuming the player got no kills in his few seconds of life). This can happen over and over, and theoretically, an infinite chain of unintentional suicide can occur. It has been seen in ranked console HQ matches for players to achieve well over 100 deaths in one game just by martyrdom. The effect is devastating on Rust, although on this map there is a higher chance of the grenade killing an enemy also, ending the deathstreak.
 * If the player placed a Tactical Insertion and killed close to it, there is a good chance that player's own grenade will kill him, thus making him drop another grenade. It is also possible that if the player doesn't respawn fast enough, the grenade will deny the Tactical Insertion, forcing the player to spawn at a normal point.