To understand the technomancer class, it is necessary to remember that Starfinder is set in a universe where magic is a real, known, fundamental force of the universe. Just as some scientists study physics, and some study chemistry, in Starfinder it is possible to apply the scientific method to the understanding and manipulation of magic itself. With that context set, let's see how the Starfinder Core Rulebook defines the class:
To the uninitiated, magic and technology are completely unrelated, but you know there are more correlations between the two than most suspect. Magic and technology are just tools, and when combined into one discipline, called technomancy, they can be far more powerful than one or the other on its own. You utilize tech to empower, harness, and manipulate magic, and you wield magic to augment, control, and modify technology. You are an expert at hacking the underlying structure of the universe itself, bending the laws of science and nature to your will. Your technomancy— which is gained from scientific study and experimentation—manipulates the physical world, weaves illusions, allows you to peer through time and space, and if necessary, can blast a foe into atoms.
The technomancer has Intelligence as its key ability score, as this modifies its spells per day, many of its core skills, and the save DCs of its spells and class features. The class has an average attack bonus, poor Fortitude and Reflex saves, good Will saves, four skill points per level, and eight class skills. The class grants proficiency with light armor and proficiency (and eventually specialization) with basic melee weapons and small arms. Like the mystic, the game's other core spellcasting class, the technomancer is a spontaneous spellcasting class. It gains access to technomancer spells, ranging from 0-level to 6th level, which represent a significant part of their power.
Technomancer spells are more likely to focus on modifying, emulating, or interacting with technologic devices, evoking or manipulating core energy types (especially fire and electricity), and manipulating or altering raw magical forces. How a technomancer operates can be strongly influenced by their choice of spells known—caustic conversion, logic bomb, and microbot assault are all useful 2nd-level offensive technomancer spells, but each comes with its own advantages and limitations.
Technomancers also receive numerous class features to represent their use of technology and scientific principles in the manipulation of magic. Beginning at 1st level, technomancers gain access to a spell cache, which initially allows you to once per day cast any one spell you know without expending a spell slot. In time, you add a cache capacitor, which allows you to store specific spell effects in your spell cache, giving them 24-hour durations. At very high level, technomancers even gain the ability to regain Resolve Points when they cast their most powerful spells, and can fuse lower-level spell slots together to cast higher-level spells (or, if you combine two 6th-level spell slots and spend two Resolve Points, even cast wish).
Technomancers also select from a list of magic hacks, at 2nd level and every 3 levels thereafter, which are special abilities focused on manipulating magic, technology, or both. Magic hacks are often fueled by spell slots, giving technomancers a new (often very flexible) way to use that resource, but can also modify spells as you cast them, channel battery power into a spell a limited number of times per day, expend (in rare cases) Resolve to create impressive effects, or even simply let you use computers to set up magical surveillance or give you additional spells known. Aside from spell selection, magic hacks are the major customizable element of the technomancer class.
Here's a sample magic hack, this one available at 5th level.
Fabricate Arms (Su)
As a full action, you can expend an unused spell slot to temporarily construct a technological weapon or suit of armor out of raw magic. You can create one suit of armor or weapon with a level equal to or less than the level of the expended spell slot × 3, to a maximum of your caster level. The item appears in your hands, on your person, or in an adjacent square. You can use fuse spells with this magic hack. A weapon can't be larger than two-handed, and the size of the item can't exceed 10 bulk. The quality of the item is average for its type. Treat this as a spell of the same level as the expended spell slot. For example, at 10th level, you could expend a 3rd-level spell slot to fabricate a weapon of 9th level or lower, or expend a 4th- level spell slot to fabricate a suit of armor of 10th level or lower. The armor or weapon persists for a number of rounds equal to your technomancer level. At the end of this duration, the item disappears. You are proficient with (but not specialized in) any weapons you create with this ability. You can't create magic items, weapons made from a special material, or weapons that are expended with use (such as arrows, grenades, or missiles) with this magic hack.
Owen KC Stephens