Eragon

The achievement is pretty straightforward as well as the level (they are all fairly linear), but in case you are having problems the video links show how to beat the level.

This was a tricky one at first... but once I learned the level it was a piece of cake. Here are the best tips I can give you:

-Just constantly run by all the enemies unless you absolutely have to kill them (when the gates closed and your locked in) You do not need to kill every enemy, in fact, you probably only have to kill about 20% of them.
-Make use of the fire attack (left trigger+B)
-The boss fight is tough because his health goes down extremely slow
-Stay to the left hugged against the small corner on the wall. Use your fire attack as soon as its charged. Spam arrows (right trigger+A) constantly.
-Make sure you save your fury!! Use it as soon as the boss fight starts and get as many fire attacks as you can while your in fury mode.

Hope these tips help! It took my over an hour to beat this level the first time on normal, but once I learned this tricks I smashed through the level on hard in around 20 minutes. Get some!!!!