Eragon

Most of this game is a breeze, but the final battle can be tricky. I found a technique that works very well, as long as you're careful:

Durza has three attacks: Magic, fireballs, and a flame breath run. The attacks wouldn't be that hard to counter were it not for the environment you're playing in: You're flying amidst the clouds, which unfortunately are almost the same color as Durza's incoming ranged attacks. It's not uncommon to not see the attack coming until it's nearly upon you. But if you're attentive and follow these techniques, you'll be fine:

To block his magic attack, simply hold LT and spam A to continuously counter his attack, sending his magic spells back at him for moderate damage. He begins with this attack, so as soon as the battle begins, start spamming the A button. You have some reaction time, so if you don't see one until it's close, you can usually still block it. This is his most common attack.

Durza will also send fireballs in your direction, which cannot be blocked and do a LOT of damage. Watch carefully for them against the background, and try to dodge them. As long as you pay close attention, you should be able to miss nearly all of them.

His final attack is to fly at you with his dragon breathing fire. This attack also does a lot of damage, so do your best to avoid it. Try this: When he starts his run, stay in the same place until he's nearly upon you, then dodge. If you dodge too soon, he'll adjust his path and hit you more often than not. Once he makes his pass, be ready with a flame attack of your own when he re-enters the screen. That does more damage to him than any other attack.

Also keep an eye out for doves to replenish any health lost. They can also be tricky to see against the background, and trying to grab them can leave you vulnerable to attack. Also watch out for the final collectible egg floating in the sky. You have to finish the battle for it to count for the egg achievement.

This technique worked the first time I tried it on both Hard and Normal.

Good luck!