I've always wanted a area where I could set the dummies def and Hp so I could test different combos on them without having kill a actual person. Once they die their health auto-resets and so do your buffs. This part may be asking a bit much, but what if the respec option was only 1 platinum in this arena so you could test tons of different builds without having to pay tons of platinum.
Have the player set their stats like you would normally see a player at your level. (About 30 def for a L10 dex bear and about 600 Hp. 50 def for a L16 bear using iron blood).