Outside (or near) each instance is an NPC who will offer a mission to each of the three instances in that zone. These missions give 1 Mark of Manaar as their reward. The mission will change once a day at midnight PST (8 a.m. GMT). These rewards one Mark of Manaar.
At level 90, a soloable Mark of Manaar mission is available from Elder Shahib Zaim at 1825,-299, 3444 , in the Hall of the Fell Blade in Paineel. These quests are soloable, but can also be completed in a group.