Introduction
Arena is being introduced as one of Blue Protocol’s “Endgame” content in JP CBT-1. Unlike your traditional “PvP” (Player vs Player), Blue Protocol puts a twist on the term. Instead of fighting players, you’ll be fighting parties of AI Mobs; hence “PvP” = Party vs Party.
What we know so far
At this current time, based on limited knowledge. Arena is a “flex-party” system. Meaning you’ll be allowed to queue up in groups of 1-6 members. (Despite the video saying it’s a 20 man content, it has been confirmed Arena is only up to 6 players at a time). Arena features 5 waves with 25 enemies in total for 3 people. These numbers will change depending on the size of your party. For example, a 6 man party will be facing 50 enemies in total with 5 waves. You have a total of 30 minutes to clear the arena. The last wave being a “Boss”. The boss is stunnable.

It is not confirmed how many times you can do arena in a day. (My guess is honestly once per day)
So there are currently 4 different “Arena Ranks”. These Ranks are “A, B, C, and S Rank Arena”.

These Arena ranks depend on the party’s battlescore. For example, in the image above. C Rank arena requires at least an “11” battlescore. These battlescores are determined by gear level, player level, skill level, and a number of other things. Your battlescore is shown on your character page.

The following are the required Battlescore for each Arena Rank
- S-Rank: 28 Battlescore
- A-Rank: 23 Battlescore
- B-Rank: 18 Battlescore
- C-Rank: 11 Battlescore
Depending on the rank, the more difficult the mobs in the arena are. My guess is the higher the lvl range of each mob. In the video it showed the highest lvl mob in the arena being lvl 15 for a C-Rank Mode Arena, despite the dev party being all around lvl 20.

When you finish the Arena you will receive GC Currency, L Currency, and Experience.
At this time, the value of GC Currency is unknown. However, it is suspected that it’ll be used to buy specific items/mats limited to the Arena. L currency is “Common currency” and is used for crafting & upgrading gear.