It`s possible to start the Bumiller Butress allready on the glacier, so you don`t have to walk for one hour under the big serac.
This way is best on spring or early summer because there is a gully filled with snow which is good to climb. If this gully has no snow enymore it get`s difficult because the rock is bad.
This route needs about one more hour to climb but the chance is much bigger to arrive on top allive.