added some some time consuming code and a return to `CalcDamage`
removed `static` from `CalcTotalDamage` so that the compiler doesn't complain that `CalcDamage` should be static
compiler wasn't happy with `totalDamage += CalcDamage(player);` or `return await Task.WhenAll(totalDamage)` because you are attempting to assign a Task to an int. Fixed it by using `WhenAll` correctly
Changed parameter name of `CalcTotalDamage` from `group` to `people` as `group` can be confusing to read as its used with linq
