Although Martyrs use cover, their primary method of attack is to rush the player, detonating the bomb in an attempt to kill the player along with themselves.
It is advisable to kill Martyrs from a distance, so they do not get a chance to detonate their bomb and inflict damage on the player. The player can headshot the Martyr, and the bomb will not detonate, or he can shoot the bomb from a safe distance, killing the Martyr and any nearby enemies.
An easy way of knowing when a Martyr is present is to listen for their loud, distinctive scream as they run at the player.
The Martyrs appear in only two campaign missions, the Afghanistan mission where they are first encountered during the back-to-back section at the beginning of the level. Their final appearance is during the raid on Ali Youssef's base where they seem to make a last stand all together in the game, even though there are very few in base with only about ten in recruit mode.