Source: Ultimate Spheres of Power
Casting
The sphere mesmerist may combine spheres and talents to create magical effects. The sphere mesmerist is considered a Mid-Caster. (Note: All casters gain 2 bonus talents and a casting tradition the first time they gain the casting class feature.)
This replaces the spells class feature.
Spell Pool
The sphere mesmerist gains a small reservoir of energy he can call on to create truly wondrous effects, called a spell pool. This pool contains a number of spell points equal to his level + his casting ability modifier (minimum 1). This pool replenishes once per day after roughly 8 hours of rest.
Magic Talents
A sphere mesmerist gains 3/4ths of a magic talent every level (the same progression as he gains caster levels).
Mental Potency
At 5th level, the sphere mesmerist can affect more powerful creatures or a greater number of creatures than normal with his mental effects. Whenever the sphere mesmerist uses an Illusion or Mind effect that targets a number of creatures or a number of Hit Dice of creatures greater than one, the number of creatures or Hit Dice of creatures affected also increases by 1. This increases by an additional 1 for every 5 levels beyond 5th.
This alters mental potency but still counts as mental potency for the purpose of archetypes that would trade this ability.