just to clear things up, the nm DOES NOT use the Self Destruch ability. the bifrons however (placeholders) uses it. any good DD with \nin can solo it. However, i'm not so sure about everyone execpt rdm taking on the PH cuz they are the ones that uses Self Destruct. without barfire and stonskin, ur pretty much dead if one of them does it and still has alot of hp left. maybe a nin with sub rdm could pull it off but i dunno. its a bit funny that a nin or another dd can solo the NM but not the ph :)
but self-destruct changes everything and can easily take u down in a sec. i did it as rdm/nin and it was a bit hard. the NM has some good accuracy and hits hard. its in no way impossible, u just have to be prepared and always have buffs on.