Something tells me it's a typo. The text says explicitly Mass Agony is an area spell, as does the range entry of "LOS (A)". One might want to check the errata thread.
Type: M Range: LOS (A)
Duration: S Drain: F – 2
A favorite of mages going through bad break-ups,
Agony inflicts an illusion of terrible pain on the target.
Each net hit scored by the magician temporarily inflicts 1
box of Physical and 1 box of Stun damage on the target.
It is not actual damage, only a measure of the effect of
the spell. The target is affected the same as if the damage
were real, with the usual injury penalties. If the target’s
damage boxes are completely filled, he is racked
with pain, unable to move or act. Once the spell is ended,
the pain and damage boxes immediately go away.
Agony affects a single target, while Mass Agony is an
area spell.
In terms of RAW, I don't think there's a difference. The "range" section says that "
[Area spells] are noted with (A) after
the range designation." and I haven't found any reference to the parenthesized descriptors having mechanical significance.
In RAI, I think it's obviously supposed to be an area spell.
