Psi

The PSIONICIST class is a 'spellcasting' class similar to Mages and Clerics,
but with several important differences. Where a Mage's power comes from
harnessing external energies present in all matter, and a Cleric's comes from
his or her deity, the Psionicist derives all of his or her power from within.
The Psionicist harnesses, shapes, and utilizes the natural forces which infuse
his or her own being. As a result, many of the devotions that a Psionicist can
practice are strictly personal in effect, and cannot be used on other players.

The prime stat for Psionic is: Constitution