I recently done some testing about Crater 2 runs. [MP 10]
You need to be tanky enough to survive elite packs there. At a large pack of Scorpions, you can reset your cooldowns easily so that part is cakewalk. (Scopions have low hp, so dps can be lowered aswell)
-> Summon dogs always for damage absorb.
-> Spam Horrify and Spirit Walk whenever possible
-> Use harvest+ Bear at scorpion packs
( Corpse spiders not really necessary for this run, i just got used to it )
If you somehow die by a hard elite pack, just leave/restart , no point to run from the beginning.
Without MS bonus item/skill, i got 80M-90M xp / hour at testing.
Im sure with better def gear and MS stuff, this run can be improved
Try it out and see how easy to get good amount of xp.
Updated video ! (now HD) :
An example run gave ~81M xp an hour ( 5 min afk included ):
As you can see i did not even use health potions at all