Defiance Free to Play

This arena is not that difficult to survive, but it is a bit frustrating to get such a high score on. You need to score 22,000 points to get a Gold trophy for the arena, and you'll be fighting the standard 99er varieties along with hellbugs starting in the third round. Beware because enemies become tougher and more numerous each round. This arena does not have a special feature.

In arena mode you score points by, obviously, killing enemies. Each type of enemy is worth a varying amount of points, with tougher enemies generally worth more points. The key to scoring well is to get your score multiplier up to x10 and keep it there as long as you can. With each successive kill you make, your score multiplier will go up by one, from x1 up to a maximum of x10. Pretty standard arcade type scoring. Also keep in mind that you will receive a 2,000 point bonus if you complete the arena without dying. You can use you self-revive without penalty, but if you have to use the A button to get back up, you will lose the bonus.

Use whatever weapons you want, but I suggest equipping an Invader class infector as your primary weapon, and a BMG that links multiple targets for your secondary, like the BM-4 Stingray. Don't worry too much about grenades for this one and equip Decoy for your Ego power to help take the pressure off.

Try to stay up top for the first couple of rounds and use your infector to take out 99ers as quickly as possible to keep your multiplier up. For the third round, drop down to the bottom and get out your BMG. This is where the linking is crucial, because this level is literally swarming with skittlerlings, with an occasional warrior hellbug. Use the infector to take down warriors while at max multiplier, then go back to town on skitterlings with the BMG. You can rack up a TON of points on skitterlings alone on this level. For the last to levels, You'll mostly want to use the infector, unless you can round up a big horde of skitterlings. Get your multipler at max and take out the goldrushers and blacklungs.

For this achievement you need to get 22.000 points or more. I suggest to try the arena few times for learning the enemies spawn locations. The keys is the chains, you can get a maximum of x10, so try to keep the multiplicator more hight you can and use this combination of weapon and skills:
-Invader
-Respark Shield
-Decoy
-Nerves of Steel
-Single Minded
-Gunslinger
-Sucker Punch
-Fortified Stance
-Thick Skinned
-Cellular Armor
-Fortitude
-Kill or Be Killed (or better if you prefer)
This combination is what i've used for get the gold and i tryed it few times before write this guide, try to use weapon and shield purple or orange if you have it and Good Luck!