Control

One piece of advice:

The ghost will continue to spawn as long as you kill the murlocs, even if you've already killed him once. This makes doing the "Murlocs... Why here? Why now?" quest (http://www.wowhead.com/?quest=9562) much harder.

Once you turn this quest in at the Exodar, however, the ghost will no longer spawn, so go make the turn-in trip before working on the Murloc quest.

You can find the Siltfin Murloc's starting at (33,26).

Bit of information on the magewraith. He is a level 10 mage type that seem to cast fireballs, arcane bolts and will sometimes cast a counterspell. He is immune to polymorph since he is undead. The arcane bolts drain 25 mana on top of the damage done. When he is summoned, he says something to the effect of "Who dares wield magic in my presence". He despawns after about 30 seconds if not engaged. If you get killed by him and are quick enough you can go back to your body and try again before he dies/despawns. The second part of the "control" used in the quest name is making sure you have enough mana after every kill to fight him. Too little and he will drain you and take you out. He never comes into melee so just hit him with everything you have.