Huh, that's interesting. It's long been contended (on the WotC boards, BG, here, perhaps others that I don't frequent) that the Nos Chirurgeon ability is Arcane Spellcasting, when powered by arcane spells/SLA's.
The Supernatural ability in PT is to convert the spell energy. 'This ability allows you to spontaneously "lose" a single [spell/SLA] to cast...' It's still being cast, and spontaneously.
The Pestilential Touch text is a cut and paste of the cleric ability, which I'll quote:
A good cleric (or a neutral cleric of a good deity) can channel stored spell energy into healing spells that the cleric did not prepare ahead of time. The cleric can “lose” any prepared spell that is not a domain spell in order to cast any cure spell of the same spell level or lower (a cure spell is any spell with “cure” in its name)...
I contend that you're spontaneously casting a spell, as that's what it says you're doing in the rules text of the PT ability. It even says which ways it's
not like a normal casting of an inflict spell. As do other Su spell abilities.
Quick examples for comparison:
Detect Thoughts (Su): A doppelganger can continuously use detect thoughts as the spell (caster level 18th; Will DC 13 negates). It can suppress or resume this ability as a free action. The save DC is Charisma-based.
Supernatural Spell (Su): ...Once per day as a standard action, she can use any one spell with a casting time of up to 1 standard action as a supernatural ability. The spell chosen must be one that is currently available to the dweomerkeeper (that is, one that she has prepared or that she knows and has a spell slot of the appropriate level available to cast), but she can decide at the moment of casting to use this ability. The spell functions as it normally would and is expended normally, but the dweomerkeeper does not require any components, does not provoke attacks of opportunity, and ignores the target's spell resistance, just as if she were using a supernatural ability instead of a spell...
Those abilities specify how they differ from casting a spell.
The Doppelganger is
using detect thoughts
as the spell, not casting the spell at all, suppressing or resuming as a free action, with the listed save DC.
The Dweomerkeeper is choosing one her spells and
using it as an Su ability, not casting it at all, but with only Components, SR and AoO's ignored (other bits like save DC's and spell level, School and Sub-school are the same, as 'the spell functions as it normally would and is expended normally, but...'). These are showing how they're different from casting said spells. The doppelganger is not using a spell at all, and the Dweomerkeeper is using a spell as a Su ability, specifically, but with differences.
Pestilential touch uses shorthand to denote the action, saving throw, components, interruptability/counterspellability and AoO status; as a spontaneously cast
Inflict spell.
QED
