You do an array of the last 10 arena DPS outputs. Take that average and compare it to the total HP for the arena level. (cap it at 99% so there's always a slight chance of failure.) This should give you a "win probability" percentage, which you could put right under the arena number. Since you know what % a given rank of a given talent will increase max DPS by, then when they buy a new rank you calculate how much that increases their DPS, recalc win probability, update number.You could pop in and buy some quick upgrades, then back out. I don't think I can handle that. But... average of dps over some rounds, and then just compare with total HP for each round. Then arena can be increased until that dps is too low. But still needs a few rounds for average dps. And it must be communicated to the player. Fuck browsers. Maybe just include a Windows build and refer to that from the web build. edit: but upgrading would be a bigger hassle than just an F5... it would need to be essentially finished for that to work.