This unusual spell is similar to phantasmal force and
other illusion magic, except that the caster is the only
creature who automatically believes the illusion. The spell
creates the illusion of any object or creature, as long as it
is within the boundaries of the spell's range. The illusion is
visual and tactile, but no other sensory stimuli are created.
Solipsism is the opposite of normal illusions in that anyone other than the caster must make an active effort to believe the illusion. Characters trying to believe the reality of the illusion must, as an action, attempt an Intelligence saving throw. A successful save means that the character fails to believe the illusion. A failed save means that the character believes the illusion to be real.
Unlike true illusions, the image created by this spell does more than just duplicate reality. The image formed is real for those who believe in it. The illusion has all the normal properties that its form and function allow. Thus, a solipsistic bridge spanning a chasm could be crossed by the priest and those who believed. Likewise, a solipsistic giant would cause real damage to those who believed it.
Those that believe in the illusion do so until the duration expires, or something causes the illusion to be revealed. For example, a bird seen flying through the illusory bridge would cause those that see it to realize that the bridge is not real, and thus end the spell for that creature.
Solipsism can create only illusions that are external to the caster. Thus, the priest cannot create an illusion that he is a horse, is unwounded, or has sprouted wings.