The Kineticist is a fairly odd class to come out of Pathfinder's Occult Adventures sourcebook. What could have been like a mixture of Carrie, Firestarter, and several characters that mostly use ESP to make people die in gruesome and horrifying ways, ended up translating into something resembling Avatar: The Last Airbender with virtually no visible ties to the occult in a book all about it. It's not particularly powerful/flexible, a bit confusing and not that well supported by first party materials (the official reason is that abilities for them aren't space efficient so they focus on something a greater percentage of characters will use) but not unplayable once you figure it out. It has the misfortune of being the only other class in the game besides Monk to use 1d6x10 GP (35 average) for starting gold, even though unlike Monk they actually need to buy armor. The design work and balance for Kineticist is shaky enough they can vary wildly in tier depending on their element: While Aether is reasonably versatile and has excellent skillmonkey ability that let it function at Tier 3 (though one of the least powerful ones), some elements are so undersupported or singularly focused they can be tier 5.
Kineticists have one major method of dealing damage: their blasts of ELEMENTAL DOOM. Using your starting element (Fire, Water, Air/Lightning, Earth, Aether (which is telekinesis), Wood (formed from the grinding of the elemental planes against the first world and Positive Energy) and Void (gravity and Negative Energy)) to create a bolt of damage with a range 30ft (1d6+1+Con mod for physical blasts, increasing by 1d6+1 every 2 levels and 1d6+1/2 Con for energy blasts increasing by 1d6 every 2 levels). These blasts deal full damage to swarms and can be readied to counterspell any spell of equal or lower level that shares its descriptor. Energy blasts target touch AC, which means that while they are subject to resistances and immunity from elements they will still hit targets most of the time. Physical blasts are less accurate (needing to hit armour and all), but deal higher damage and bypass spell resistance because a Kinetic Blast of Rock is still a VERY STRONG ROCK at the end of the day.
Naturally, just shooting things at 30ft range with elemental bolts isn't going to help you as the difficulty mounts. This is where the 3 major mechanics of the kineticist come in. These three are Infusions, which enable you to alter your blast so it does a variety of various things from boosting range, making construct weapons of your element (like swords, whips, fists and more), Wild Talents (which vary from minor passive powers, to full blown spellcasting within specific elements) and the balancing mechanic of Burn. Burn is designed to prevent kineticists from simply dropping a pillar of fire on the enemy and walking through the remains of their foe. To use your infusions and some wild talents, you need to accept burn, which deals 1 point of non-lethal damage per character level per point. Not exactly too bad since as a Con based Class you are at least somewhat good at soaking up damage. The issue is that at first, you cannot take more than 1 point of burn per round, rising to 2 at 6th and going up by 1 every 3 levels. A variety of abilities exist that reduce the total cost of burn you take in a round, with some even providing benefits from having a certain amount of burn.
When you get to 7th level as a Kineticist, you get access to your second element/version of your initial element. This doesn't seem like much until you factor in the added power of composite blasts. By taking Burn you can unleash a blast that possesses 2 elements or a stronger version of an element you already possessed. In any case, most Composite blasts deal double the damage of a basic elemental blast, which by the point in time that you get it, can be outright lethal to most simple targets. This is also added into the fact that you now have access to all the infusions and wild talents of this new element, though at a slower progression.
In the end, Kineticist is a class with some interesting abilities but is much more specialized into a single area than most conventional casters. Oh and the iconic character is a Loli that's not entirely rules legal. She's under the minimum starting age and small size. If you use her sheet for an official game you can't level up without some fundamental changes.
Remember how the opening said they weren't well supported in first party material? Well just as 3.5 Psionics were niche, a pain to figure out and under-supported by first party material (and what little there is often pure garbage), but had good support from third party publishers, so too does Kineticist. The class's dependence upon a major choice (element) at levels 1, 7 and 15 and smaller choices (wild talents and infusions) at every level but 7 and 15 while having almost no feat support mean the class actually has quite a bit of room to expand on. As such third third party publishers (Primarily Purple Duck Games and Legendary Games) have gone wild with the class, introducing new elements, both normal (light, sound, metal, mind, poison) and bizarre (time, blood), as well as tons of infusions, wild talents, archetypes and Kineticist specific feats.
|The Classes of Pathfinder|
|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|