The [F] Colosseum, owned by Gladius, is one of the town areas that you can enter. Unlocked after you defeat the Terminal, the Colosseum is an area where you can defeat enemies to gain Soul Shards, Skill Points, Ascendant Weapons and Wardrobes/Adornment Shards in combination with the typical rewards from fighting enemies outside the Colosseum. Keep in mind that the risks fighting these enemies are the same as outside the Colosseum so make sure to be prepared and run when necessary. There are multiple options when in the Colosseum as shown in the example image below.
[E] Graveyard Edit
The graveyard is where all your past files are recorded when you die in a run. Note that they will only record deaths from either Classic or Lunatic mode. It records various stats about the character in the following format: [Record #] >> [Character Name], the [Difficulty Level] Lvl [Lvl #] [Body Type] [Gender] [Character Origin] [Character Class]
Below is an example image of a graveyard.
[R] Training Edit
The Training area is where you can practice new combat strategies. You will face a training bot that will restore its health back to its max after going below a certain HP threshold(likely to be 50%). It's nearly impossible to die from the bot(1-1 attack), however you still take damage from your own gear e.g. Unstable and Vamp. When you're done with training, you can run away from the bot with a 100% chance. Keep in mind that if you do have a charged ult, you will need to use your ult on the bot before running away due to the standard combat mechanics.
[Q] Quest Edit
Just like the quests at the Blacksmith and the Market, the owner (in this case being Gladius) requires a certain quest item, this being Garbunzo. Retrieving this for him will grant you a random item.
[T] Talk Edit
Just like the other townspeople, you can talk to Gladius for some light, humorous conversation.
 Arena Edit
One of the main elements of the Colosseum is fighting Arena opponents. Before you can fight an Arena opponent within the Colosseum, you must use a silver key to enter. Once you defeat an Arena opponent, you gain 1 Rank point, increasing indefinitely as you defeat more Arena opponents. You need to defeat one of these opponents to go beyond the Rusted Gate. Arena opponents can also appear in random events and should you choose to fight, you will immediately engage with the Arena opponent without using a silver key. Additional info concerning the Arena can be found in the Game Manual Images section of this page.
 Questing Keystone Edit
This area contains 4 portals, providing a potential maximum of 4 dungeons active at one time. Each dungeon has a certain number of enemies(min. of 2), the last one being the boss. The boss has a considerable amount more health than the other enemies, but damage, affixes, etc. still vary just like the other enemies. After pressing 77, 88, or 99 after defeating a boss will open a keystone chest, always containing a soul shard, but possibly other items as well. Additional info concerning the Keystone Dungeons can be found in the Game Manual Images section of this page.
 Ranked Matchmaking Edit
Ranked Matchmaking is where you will be able to gain additional skill points beyond the 1 that you gain after every level. Before you are able to participate in Ranked Matchmaking, you must be at least level 30. Once this is achieved, you will be placed through 5 Placement Matches. Completing all 5 will likely put you in either Copper or Bronze as well as giving you 3* skill points to use. Each league is split into 3 sections with the exception of Grandmaster, generally requiring you to get 300 ELO points before you are admitted into the next league. Additional info concerning the Ranked Matchmaking can be found in the Game Manual Images section of this page.
* : Requires verification
|League Name||ELO range|
 Retrain Masteries Edit
Here you can reset all of your mastery points for a price. This is useful when you equip a new weapon type, but do not have any mastery points for that type. Keep in mind that you will also be set to 1 HP, so remember to use a heal charge or sleep before entering into any combat.
Game Manual Images Edit
These images were taken from the in-game Game Manual. To access the Game Manual, press [C] Character while in the main screen. Then press  View Game Manual. The Colosseum info was taken under  Colosseum. Additional information was gathered from  Miscellaneous.