My Centum experience has been an incredible one so far, and Arena was no different. The trials are more challenging than the ones of Gladius and are guaraunteed to improve you in one way or another.
The leaders/elders are all very supportive and helpful, providing advice as well as pushing you further. Everyone there is willing to help whether it be with troops or attacking advice. It is also a great place to have a chat about anything you like as the people there are very sociable

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If you haven't already, I would definately recommend applying for Centum right now, it is an incredible experience!