For the colosseum, I currently have survival, team survival, and PvP as options for entering the arena. Only one player may use the colloseum at one time (except if your doing team survival, or PvP). Survival makes you survive for x number of rounds (not decided yet) depending on the diffuculty that you picked before you entered the colloseum, team survival is the same thing, except you face more/stronger creeps depending on how many players are participating. Each player participating gets gold depending on the number of monsters killed and how long you lasted, on survival/team survival. XP is also decided on survival/team survival as being an % of your Colosseum XP. More information:

The game begins as you choose a character from one of the tiers. Your colloseum XP is then set to 1.00. Over time, your colloseum XP goes up up to a maximum of 2.00. However, every time you participate in the arena, your colloseum XP goes down, up to a minumum of 0.00. When you defeat creatures in the colloseum, you gain extra XP if your colloseum XP is greater than 1.00 and less xp if your colloseum XP is less than 1.00. This is because colloseum XP affects your Current Experience Rate while only in the colloseum. Say your colloseum XP was 1.20 and your current experience rate was 60%. If you went to the colloseum and picked survival, then your current experience rate would be 72%, however if your colloseum XP was 0.8 and experience rate was 60%, then your current experience rate would be 48%. To those who understand the pattern, your current experience rate would then be (colloseum XP * current experience rate) in the colloseum. Colloseum XP saves with your character. This creates a reason to go to colloseum, and a reason to not farm in it forever, while also making sure the player kills creatures outside the colloseum.

PvP is between two players. To enter in PvP, it is similiar to team survival in picking the player, however you can pick only one player. After the player is picked, the two players (the player picked, and the player who went up to the colosseum director) go into the colosseum and fight. Killing another player in PvP does not yield any XP. If the person who first created the PvP duel chose a battle for honor, then the victor gains one honor point, while the loser loses one honor point. The battle also yields no honor if the loser is 100 levels below you and if he/she has no honor, however it gives triple the honor if the player is 100 levels above you. When you create a character, he/she starts with 15 honor. Honor can be used to buy PvP gear for Honor, Gold or Platinum Coins(will not be implemented in next version, simply because this all is just taking way too much time.) A Battle that does not include honor can also be selected. Honor saves with your character.

I will add future modes in the future (eg. Team PvP, Doppleganger(defeat a stronger copy of you to win gold/stuff)). Now I have a question. First, dwhat type of monsters do you want to be faced in the arena? I can add monsters that are already in the game, such as ogre overlords/nerubians in the arena and only increase them in amount for a larger number of players, or add custom monsters for each round faced in the arena? (will take more time, but will make the colloseum more unique). Second question is, how do you think of this idea?

Survival and team Survival also get harder if Chaos world is on.

P.S. (It took me 40 minutes to write this post)