I have an idea for a building that could be added afte the lab and companion pets.
This building is the Training Arena:
How it should works:
Two or more people after entering the Arena will be able to duel with each other or one of them will take control over arena(sice now he'll be trainer and he will control spawn of mobs and placeing of traps) and rest of them (splited into 4-person teams it will mean that Arena itself also split into sectors over which trainer will have separeted control) will fight against the enviroment controled by trainer and under rules seted by trainer (of course they can't be too dificult for eg. defeat 100 tier 3 zombies in proto set without any death). Also it should be posible to allow single person to use it by creatinga training programs or giving him creator of programs like this wich will control spawn of mobs and positions of traps just like trainer, but automatically. To don't make it overpowered there will be no option to train boss fights (only with weaker dummys).
Benefitsof this Arena:
Training like this will increase players skills at playing in game what will mean more people who will be able to achive vanguard rank and also compensate the skills sof thous who reached this rank mainly thanks bought energy to make them, as good players as, good they should be with rank of vanguards.
Also it will allow to test weapons, and test more things than only damage dealing to diffrent types of enemis but also things like distance of shot for guns or landing of sword, whe we can use them safely and when we should try other weapons becous landing is so big that we are going with it directly into trap and so forth.
Place of it and payment:
Entrance to this Arena should be placed in Garnison at the right edge of location also it can replace or be conected with Advanced Training Hall.
About payment revives will be for free like in all training locations eventually it can be a litle payment for entering it depending on tier, but it could be conidered as greed and ther shuldn't be any payment for using it.