Basically same requirements as t3 to get in, and instead of having the basics in the "advanced" training hall, it has all the things to test in t3 so that people can get standardized info on armor and weapons, this should include, separate rooms each with one different active monster (to practice / test timing, everything from jellys to the rolling spike things is FSC) a way to inflict any status(at a t3 level) this can be an add on to the training hall (maybe charge entrance fee? monsters have no drop though) either way it is currently difficult to test out the finer points of Spiral knights (for example asi ultra + damage low vs asi max) and I feel this would be easy to make with great reward for the more serious community.
I always wanted a "testing" area for my new gear. You could select the monster families (or specific monsters) and choose an arena layout. That would be fun to have when you have to wait for ME regenerating and also fun with friends. But you would get no rewards or achivements by it. WE NEED THIS!!!