Basically as the title states. After level 100 the manastorm environmental modifiers make it impossible to afk (even for a few minutes) without getting blown up in some way. And as the runs are getting slower and slower, doing 10 levels in one go can take a long time.
My suggestion is either make the checkpoints for entering 5 level increments. Or make it so the starting bubble remains forever untill you step outside once, and then last only two minutes.
On top of that the vendor spawns seem to be way too rare to actually sell your stuff. My 100 bag slots are full after 5-6 levels generally. Trying to sell stuff while getting bombarded every 10 seconds is also quite rough.
One final unrelated note, the Inquisitor Whitemane manastorm level is nearly impossible when combined with the modifier that constantly spawns mobs from the portal. Her AOE ressurect will bring forth an army and while you could pile stuff in one corner, mobs will keep coming during the fight making that tactic irrelevant.