Mad Moxxi's Underdome Riot - Borderlands Guide

Mad Moxxi's Underdome Riot - Borderlands Guide
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Am I Ready for the Underdome?

You can technically go to the Underdome at level 10 if you really want to. Just like with The Zombie Island of Dr. Ned, you pop on over to a New-U station and warp on over. I wouldn’t recommend it though. The Underdome is tough, requires a variety of weapons and skills to complete, and it doesn’t give experience. For this piece of Borderlands DLC, I’d say wait until 50. In the meantime, why not go finish up Zombie Island?

In Mad Moxxi’s Underdome Riot, just like Zombie Island, the enemies will be the appropriate level. If you’re 10, they’ll be 10. If you’re 50,they’ll be 50. So why not go earlier? Think about your level 10 character, or even your level 20 character. Were they equipped to handle Lance soldiers, Badass Fire Skags and Arch Guardians?

If you’re not ready to go full bore into the Mad Moxxi content yet, I’d still advise you to go over there early and grab some bank slots. It’s always nice to have room to store loot, especially at early levels when your inventory hasn’t been bulit up yet.

As a side note, this guide was written just after the release of The Secret Armory of General Knoxx, the piece of DLC that raised the level cap. I haven’t had a chance to tackle Moxxi at level 61 yet, but when I do, I will add a level 61 section to this guide if it is warranted.

What Did I Get Myself Into?

The Underdome is a hub that links to three different arenas, each with their own enemy set and landscape. Each arena has two different levels of challenge. You’ll have to complete the short challenges before you approach the long ones, and even the short ones take some time to complete. You’re not going to knock out The Underdome in a day.


You’re not going to want to go it alone either. If you’ve got a friend to play with, good. If you’ve got three friends to play with, so much the better. Dying while playing solo means you lost the round. Dying in a group means that you’re forced into the penalty box. As it happens though, the penalty box is a pretty slick sniping spot.

Be prepared for everything. Depending on the arena you fight in, you’ll be up against a variety of enemies. Before you even try to challenge The Underdome, you’ll need a good caustic weapon, a good fire weapon, and a way to take down Guardians. For some people, that’s a good shock weapon. For others that means a specific build. Either way, you’ll need to be ready.

Lilith’s Siren Song

Things are a lot different when you’re playing Moxxi. Defense is prized over offense and builds get complicated. You’ll play your Siren a lot differently than you’re used to, using all of your skills to defend and evade rather than the traditional all out assault. I’m not going to go through the e


ntire build, because by this point you know what your skills do. We’re going to build on the Firefly build from my Zombie Island guide, and make a few changes along the way.

First off, you’ll still want that Firefly class mod. Lilith’s got a few team bonus class mods, but they fall short compared to other classes, so you get to stick with a fun one.

I love 5/5 in Radiance. It’s an incredibly underrated skill. Sure, shock damage hits slowly, but it’s a lot of damage over time. If you phasewalk past an enemy early on, Radiance will keep him hurting for a long time. Constant damage means no shield regeneration, and that’s a very good thing. Radiance is also a nice bonus on top of your Phoenix damage.

Why not 5/5 in Mind Games? Think about how fast you shoot, especially if you’re sporting a Double Anarchy. At 2/5, you’ve got a 10% chance to daze an enemy. That’s once every ten shots. If you up it all the way to 5/5, you’ve got a 25% chance, which amounts to one in four shots. If you’re using a nice quick SMG, those extra six shots only take a fraction of a second. That’s not worth three skill points in my book.

Mordecai - Hunting for Survival


It’s so hard for me to use Mordecai without a gunslinger mod, but that’s just what you’ll want to do if you plan on getting your group through Moxxi. The health regen that’s built right in to a Survivor class mod will save the day on countless occasions, especially when the rules eliminate your shields.

The problem with the Survivor class mod is that the bonuses it gives are pretty lame. Swipe isn’t great, especially since Moxxi drops health and ammo at the end of each round. Fast Hands is a bit of overkill if you’re a pistol user, since you’ll be reloading ridiculously fast as it is. The best of the three is Riotous Remedy, which I only really put points in because of the bonus.

My preferred Mordecai build can be played in a pretty straightforward manner. I’m a big believer in pistols and revolvers, but make sure you pack something with high zoom in case you get stuck in the penalty box.

Remember, Bloodwing is an essential part of your repertoire. Send him out to daze the enemies at every opportunity. Slower enemies mean easier kills and fewer dead teammates.

Roland - Soldiering On


If you’re playing a Roland, you’re instantly everyone’s best friend. In Moxxi, you get to do a little bit of everything, and you’ve got some versatility in your build. Though I prefer shotguns for maximum zombie killing potential, machine guns and combat rifles are the weapons of choice for The Underdome.

Grab a Heavy Gunner class mod. You’ll be doing enough to help the team through your skills that you won’t really need to give bonuses through your com. You can even go 5/5 in all the skills that matter to a Heavy Gunner, you’ve got room.

In fact, you can really do whatever you want as long as you hit the one essential skill.

Stat. You need Stat. Your friends will love you for having it. Who doesn’t love a mobile healing station with a machine gun attached? Even if they’re not around, you’ll get the health bonus. You can make your own judgmentsabout Cauterize, but it’s never worked well enough for me to bother with it.

Once you’ve got Stat out of the way, I’d suggest grabbing the two shield skills at the beginning of the Support tree and then moving on over to the Infantry tree for the fun stuff. Impact, Metal Storm and Assault are a combination that makes you a force to be reckoned with on the field.

Going Berserker with Brick


Alright, Brick players, you get off easy. You get to do that whole running around and hitting people thing you love to do so much. You get to turn Borderlands into Punch-Out! and you don’t even have to rock a Titan class mod. You can go Skirmisher as long as you’re giving the team a maximum health bonus.

As far as your build goes, The Underdome is a dangerous place where the enemies will do their damndest to chisel away at your health. Your job is to make sure that they don’t. Survivability is the name of the game.

Increase your maximum health with Hardened, increase your shields with Safeguard and put some points into damage resistance to boot. But most of all, you need to rage as much as possible.

Take Endless Rage to keep that health regen and damage resistance going. Take Short Fuse to get back to your rage quicker. Most importantly though, keep it going. You need to keep the heat off of your more fragile teammates and you need to stay alive while doing so.

Rounds and Waves

In each challenge there are either five or twenty rounds. In each round there are five waves. You need to complete them all to move on.

The first wave is a standard assortment of enemies. It’s usually skags and bandits, and it’s a nice fun time for everyone involved. Except the skags and the bandits.

After you warm up, you get to face the Gun Wave. There might be some Lance soldiers depending on the map, but you know how to handle them. The Gun Wave is cake.


The Horde Wave is when things start to get a little scary. Psychos, Burning Psychos and Midget Psychos come running from all corners of the map to converge on you. If you pick a nice spot to hole up, you can just shoot straight and take them out. If there’s a headshots only rule in effect, or worse yet, an enemy speed boost, you may be in for a rough one.

The Badass Wave. Yikes. .This one can get really rough. You’ll be fighting elemental skags, Badass Engineers and of course, Guardians. If you’re in a ruleset that gives the enemies a bonus to accuracy, those Arch Guardians can be real trouble. Your best bet is to stick together and take out the hardest stuff right off the bat.

Boss Waves are generally where it gets easy again. If you missed out on pickups you might be low on ammo, but bosses are simple. Tank and spank. Get someone to take their attention and then burn ‘em down.

Final Words of Wisdom

The Professional

Grab Tough Guy shields. There will be rounds where you lose your shields completely, but you’ll still have the benefits. Shields with a bonus to health can prove invaluable here.

Consider the advantages of dying early. If you’re a great sniper, you may be more beneficial to your team up in the penalty box than down on the ground. Die early on harder rounds and help out where your partners need it.

Think soccer. The Underdome isn’t about the quick win. It’s about endurance. Those longer challenges last for hours so don’t blow all your energy early on.

The real secret to finishing off Mad Moxxi’s Underdome Riot, just like with Left 4 Dead, is teamwork. Stick together when it gets rough, and spread out when it’s easy. If your Siren does better meele, let your Siren go melee. If your Brick is great with explosives, then by all means go explosive. There’s no rule set in stone. If you work to each other’s strengths you’ll do just fine.

This post is part of the series: Borderlands Walkthroughs and Guides

For information on everything Borderlands, check out our series of walkthroughs and guides.

  1. Borderlands - The Zombie Island of Dr. Ned Walkthrough and Build Guide
  2. Borderlands - Mad Moxxi’s Underdome Riot Guide
  3. Borderlands - A Guide to The Secret Armory of General Knoxx
  4. How to Kill Crawmerax - A Borderlands Guide to Taking Down the Invincible