Underdome gameplay mechanics

Gameplay in the coliseums of The Underdome consists of waves and rounds. Each round consists of five waves.

Waves

 * 1)  Starter wave:  This is a relatively easy mixture of everything you will fight in the next couple of rounds.
 * 2)  Gun wave:  Every enemy will have weapons. No skags or psychos will be present, only regular bandits/brutes or Crimson Lance.
 * 3)  Horde wave:  Psychos - Many psychos. All types (regular, burning, badass, and midget).
 * 4)  Badass wave:  Don't be intimidated. Few of the enemies are actually badass variants, but each will come with a couple of smaller equivalents; bandits are upgraded to brutes, Lance Infantry are upgraded to Engineers etc.
 * 5) Boss wave: A random boss is selected for you to fight, as well as a few henchmen. These include Nine-Toes and his skags, Bone Head, Baron Flynt, Hanz and Franz (always without henchmen), Master McCloud, King Wee Wee, Reaver, Sledge, One-Eyed Jack, Taylor Kobb.

Loot
 * A random selection of weapons will appear at the bottom of Moxxi's tower once you defeated the boss and his henchmen. You will have about ten seconds before the weapons disappear again.
 * It appears that not all players see the same selection of items. Some weapons will only be visible to some players, so be sure to check for yourself.
 * It is possible to get loot from enemies as well, but it's extremely rare.

Rounds
Every round will increase in difficulty. Every five rounds the amount of enemies to kill increases. More enemies will teleport into the arena over time within each wave.

Rules
Rules, also referred to as Moxxi's Maxims (similar to "Skulls" in ODST Firefight, basically Power-ups or Modifiers) will be introduced at:


 * One modifier after the 1st round
 * Two at the start of the 5th round
 * Three at the start of the 10th round
 * All four at the start of the 15th round

Examples are listed below.


 *  --weapon-- Challenge:  A random weapon type is chosen (for example, Shotguns). That type does more damage and everything else does less. Eridian weapons don't seem to be included.
 *  Beef Cake:  Enemies have more health.
 *  Body Shots:  Critical hits do less damage.
 *  Close Combat:  Players will be less accurate, but will do much more damage.
 *  Dead Aim:  Enemies are more accurate.
 *  Elemental Challenge:  Elemental attacks will work better, normal attacks will do worse.
 *  Dodgeball:  Enemies actively dodge your attacks.
 *  Get Some Air:  Low gravity.
 *  Headshot:  Critical hits do more damage, everything else does less.
 *  High Speed:  Players and enemies move faster.
 *  Hot Potato:  ???
 *  Ironhide:  Enemies have better shields.
 *  Kick A*%:  Enemies will deal more damage.
 *  Loaded:  Enemies have larger magazines.
 *  Naked:  Your character has no shields, but will slowly regenerate health.
 *  Overclocked:  Enemy shields regenerate faster.
 *  Regeneration:  Enemies regenerate health.
 *  Spastic:  Enemies move and reload faster.
 *  Vampire:  Your character's health constantly degenerates, but can be refilled by killing an enemy.
 *  Weapon Masters:  Enemies spawn with higher quality weapons.

Penalty Box
If a player fails to get a second wind in a multiplayer game, they will respawn in the Penalty Box on top of Moxxi's tower. The character will be stuck up there, but can still help the rest of the team by shooting down on enemies. Players in the Penalty Box will not be targeted by enemies and their health will not drop below one point. Players will re-spawn at the bottom once the wave is finished, or the entire party is wiped out.