Psychic is one of the new Pathfinder classes introduced in Occult Adventures, and the only full caster among them. They are an intelligence based, spontaneous casting, occult caster using a proprietary spell list.
As an occult caster, Psychic is totally screwed by its spells requiring emotion components, which fail when under non-harmless emotion effects. Non-harmless emotion effects include Shaken and other fear effects, which are easily inflicted and a good number of monsters can inflict without spending an action. While Mesmerist has non-casting options, the ability to remove fear, spells without emotion components, and (in a worse case scenerio) use a metamagic rod of Logical Spell since it's only a 2/3rds caster, Psychic is totally screwed by such effects. This is really bad as horror and Yog-Sothothery are stated elements of "occult" campaigns. This also means Android are pretty much totally locked out of the class, which is a shame since it's the only base class in the game to have technology focused options (see down). It also means they don't suffer from ASF despite their lack of proficiency, letting them wear 0 ACP armor without penalty.
Instead of a bloodline, Psychics gain a Discipline that functions largely the same. Really, the most notable thing about these is some of the source options are really fucking weird. Psychedelia gets psychic powers from getting high on drugs. Mindtech has merged with a computer, and has a series of tech-based amplifications supporting it (sadly these are all largely terrible). Rebirth is a pretty standard one, but is notable for its sheer power: It gives a spell known (of one below the highest level you can cast) that can be changed every day and can come from any one casting class in the game (which can be changed at each level).
Aside from their casting, their other class features consist of Phrenic Amplification, which allows you to spend points from your Phrenic Pool to add bonuses to certain spells. Problem is these abilities are MAD, since the Phrenic Pool needs either Wisdom or Charisma (determined by Discipline) despite psychic being an intelligence based caster. Further, the most powerful options by far are also the most boring by far: Spend Pool points to increase the DC of your spells and spend pool to overcome the immunity undead have to Mind-Effecting spells. As these two are essentially mandatory, and you need to blow feats or wait till level 7 to get the third, the amplification picks do a poor job of letting you customize the class. At level 10 you get access to Major Amplifications, which are more consistent in balance but come late.
They also get... a few iconic spells as SLAs. This is pretty underwhelming and screams filler.
Like most of OA, Psychic is a less than stellar class design saved by the sheer power of being a caster. Said sheer power of casting makes the Psychic tier 2 since while its spell list isn't too well supported (only hardcover books and late softcovers) it still has plenty of spells capable of trivializing encounters. Rebirth discipline may be tier 1, as might the Amnesiac archetype.
|The Classes of Pathfinder 1st Edition|
|Core Classes:||Barbarian - Bard - Cleric - Druid - Fighter - Monk |
Paladin - Ranger - Rogue - Sorcerer - Wizard
|Alchemist - Antipaladin - Cavalier |
Inquisitor - Oracle - Summoner - Witch
|Arcanist - Bloodrager - Brawler - Hunter - Investigator |
Shaman - Skald - Slayer - Swashbuckler - Warpriest
|Kineticist - Medium - Mesmerist |
Occultist - Psychic - Spiritualist
|Ultimate X:||Gunslinger - Magus - Ninja - Samurai - Shifter - Vigilante|