The descriptions of the spells blasphemy, holy word, word
of law, and word of chaos say that if you are on your home
plane, casting one of these spells banishes those not of your
plane back to their home planes, and creatures native to
your plane (with an alignment opposed to the spell) suffer
various ill effects. Several evil outsiders have this spell-like
ability. How does this spell-like ability work for an outsider
on the Prime Material Plane, which is not its home plane.
Conversely, when these outsiders are on their home planes,
how are these spells useful? For example, what use is word
of law to a devil on Baator, where just about everything is
lawful evil?
If the subjects of any of these spells are not extraplanar
elementals or outsiders, they suffer effects according to their
alignments and Hit Dice. In spite of what the beginning of the
third paragraph in each spell’s description says, you don’t have
to be native to the caster’s home plane to be affected.
If the spell’s subjects are extraplanar elementals or outsiders,
and the caster is on his or her home plane, the spell blasts the
subjects back to their home planes. These creatures also suffer
effects according to their alignments and Hit Dice. Being
returned to their home plane is an additional effect, not an
alternate effect, as the spells’ descriptions imply.