Charged Up

Stand near a Tainted Arkonite Crystal, get Arkonite Empowerment buff. Kill 30 monsters while having the (de)buff. Note that if Assault on Shattrath Harbor is the garrison daily, the crystal can be interacted and destroyed, gaining credit towards the quest, which you don't want to if you are after the achievement. Therefore the best opportunity to do the achievement is during days which is the not the daily.

Places I found the crystal:
41, 21
40,17.7

!ATTENTION!
Do NOT break the Crystal, you need to kill mobs around the Crystal, don't do like me and think you'd receive a buff to go around and kill mobs. If you break the Crystal you will have to wait for another one to spawn.

Not as difficult as you might think on a high population server when everyone, their mom, their Grandpa, and Long lost Uncle Hester are doing a daily here.

1) Go to 40.1, 17.7. It's a nice out of the way location from the main path.

2) The Tainted Arkonite Crystal here has a respawn of approximately 10 minutes.

3) What you want to do is kill all the mobs in the immediate area, whether the crystal is up or not. That way people won't bother you and they won't waste your time hanging around. Being a hunter, it's easy to track mobs nearby, and I kept at least one freeze trapped and one on the pet in case the crystal spawned.

4) When the crystal finally does spawn, pull any mobs within range till they get the debuff and make sure you have it as well, be nice & close, and kill the mobs.

5) One by one the mobs you killed earlier will respawn, and you should get to 30 in no time, and people shouldn't be around because there's nothing to kill here, in their mind.

6) If someone shows up and 'uses' your crystal and it disappears, don't fret or get mad they're doing the daily quest just like you, just hang out another 10 minutes till it respawns. Rinse & repeat.

7) Achievement Completed.