From wow.incgamers.com

Quest

Commander Thomas Helleran: After you bring down the defenses of the Scourge summoning circles, you must confront the acolytes who protect them.

In thruth, these are not men. They are shadows, some of the Lich King's most frightening creatures. They can be revealed using the necrotic runes they carry, and then destroyed with magic or strength of arms.

Quest Objectives

Go to a summoning circle and kill a Shadow of Doom, then return to Commander Thomas Helleran at Light's Hope Chapel in Eastern Plaguelands.

Rewards

• Blessed Wizard Oil x 5
• Consecreated Sharpening Stone x 5

Conclusion

Soon

Tips

When the crystal's health reaches 0%, four summoners appear. Their name is displayed in yellow text. Talk to them. They will give you the option to use 8 Necrotic Runes to stop their casting. At that moment a level 70 elite Shadow of Doom will spawn to attack you. Only you can tag it. Make sure to farm those 8 Necrotic Runes.