Wee Jas said:
Isn't it impact damage? So DR would effect it? Like dropping a wall of stone on something with DR. DR would absorb some of the damage right?
Creeping Doom is another example. It specifically says DR reduces the damage from the bugs.
The damage is from a spell, and spells ignore DR. That's the ruling the Sage made in the case of Blade Barrier, and this would seem to be a similar case.
On the other hand, The wall of stone created by the spell is not magical in nature, and would be subject to DR as normal.