What expansion is needed to unlock more level progression past level 30? Due to the swap from battle.net to steam, Forsaken is unable to be purchased.
I wanted to add a little more information that you may not be aware of with regards to what's happening October 1st. With New Light, your characters will no longer have levels. Instead, there will be seasonal ranks that are shared account wide. These seasonal ranks will give you 1 power for each you have. The seasonal ranks do not have a limit, and are tied to seasonal rewards. At the end of the season, they reset back down to zero. Additionally, all your gear on character and in your vault will be brought up to power level 750, and all players will be able to grind up to the maximum power level of 960.
Forsaken is required to go past level 30.