Only the spells subject can see the phantasmal killer.
The character see only a shadowy shape. The subject first gets a
Will save to recognize the image as unreal. If the subject fails,
the phantasm touches him, and he must succeed at a Fortitude save
or die from fear. Even if the Fortitude save is successful, the
subject takes 3d6 points of damage.
If the subject of a phantasmal killer attack succeeds in
disbelieving and he is wearing a helm of telepathy, the beast can
be turned upon the character. The character must then disbelieve
it or suffer its deadly fear attack.