My DM is saying that SoD (Save or Die) spells, (Phasmasmal Killer being the spell in question.) still deal "damage," just doing enough damage to reduce hit points to -10, and are thus turned into non-lethal damage by regenerators (trolls being the example encountered.) So unless an SoD can be shown to deal CON damage instead of HP damage, it won't kill a troll.
How can I refute him? Or is he right?
How can I refute him? Or is he right?