Order any points plus pay item. Don't order vouchers, they won't get cancelled. Exact item depends on how much points I need to hide to make MB zero. So, that keeps changing. There is a filter to display items by specifying points range and then sort them via points to get one closest to ur requirement.
Anyway it's too complicated to know how many points u need to spend to make MB zero and not needed anymore, as ER to MB movement thing is fixed, assuming u have at least 300 MB points.