City Defender

This achievement can be obtained with a single button press, given the right conditions :

http://www.wowinsider.com/2008/11/03/the-thunderstorm-of-thunder-bluff/

Most of this has been said, but I'll consolidate it into one post.

What you DO have to do:

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• Deal damage. The only way around this requirement is if you're in a party/raid and one of your members gets the kill, in which case you will get credit even if you did no damage.
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• Be inside your city. You will get no credit towards this achievement if you yourself are not inside the city, even if you kill a target that is.
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What you DO NOT have to do:

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• Get an honorable kill. Any player of the opposite faction, regardless of level, will count towards this achievement.
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• Land the killing blow. As long as you do any amount of damage to the target or are in a party/raid with someone who gets the kill, you will earn credit towards this achievement.
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• Kill a target physically in your city. As long as you yourself are inside of the city, killing a target will contribute to this achievement, even if the target is outside of the city.
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The best time to get this is now! (Midsummers's Fest.) I just sat at the Org flame (didnt have anything better to do) and just put a flame shock on them when they got to the flame..started with 8/50 and got to 50 in no time.