From Compendium of Worldly Lore
Mysterious and elusive, the unseen seer trades in secrets. Subterfuge is her business in the same way that death is the assassin's business, and she uses her magic to help her gather other people's secrets while keeping her own.
Because an unseen seer specializes in stealthy information gathering, this prestige class is especially attractive to rogues. Ninjas, scouts, and spellthieves might find it equally beneficial. Regardless, these characters must master the basics of arcane divination magic before entering, whether by multiclassing as a wizard (typically a diviner), sorcerer, or other arcane caster. The beguiler can qualify as an unseen seer without multiclassing, and though bards make good unseen seers, they typically must multiclass to meet the skill requirements.
Role: Spell Utility
Characteristics: Divination focused arcane thieves and sneaky folk that do their best to remain one step ahead
Source: Complete Mage
Game Rule Information
The Unseen Seer has the following game statistics.
Abilities: Dexterity for getting in your additional damage off sneak attack, Whichever arcane casting stat you use, Intelligence or Charisma
Alignment: Any
Hit Die: d4
Starting Gold: N/A
Class Skills
The Unseen Seer's class skills are Bluff (Cha), Concentration (Con), Decipher Script (Int), Diplomacy (Cha), Disguise (Cha), Forgery (Int), Gather Information (Cha), Hide (Dex), Knowledge (all skills, taken individually) (Int), Listen (Wis), Move Silently (Dex), Profession (Wis), Search (Int), Sense Motive (Wis), Spellcraft (Int), and Spot (Wis).
Skill Points at 1st Level: (6 + Int modifier) × 4
Skill Points at Each Additional Level: 6 + Int modifier
Class Features
All of the following are class features of the Unseen Seer.
Weapon and Armor Proficiency: A Unseen Seer is proficient with whatever they were already proficient with prior to taking levels in this class.
Spellcasting: At each level, you gain new spells per day and an increase in caster level (and spells known, if applicable) as if you had also gained a level in an arcane spellcasting class to which you belonged before adding the prestige class level. You do not, however, gain any other benefit a character of that class would have gained. If you had more than one arcane spellcasting class before becoming an unseen seer, you must decide to which class to add each level for the purpose of determining spells per day, caster level, and spells known.
Damage Bonus: At 1st level, the extra damage you deal with your sneak attack, skirmish, or sudden strike ability increases by 1d6. If you have more than one of these abilities, only one ability gains this increase (choose each time you gain this benefit).
Your sneak attack, skirmish, or sudden strike damage increases by another 1d6 at 4th level, 7th level, and 10th level.
Advanced Learning Ex: At 2nd, 5th, and 8th level, you can add a new spell to your spellbook or list of spells known, representing the result of personal study and experimentation. The spell must be a divination spell of a level no higher than that of the highest-level arcane spell you already know. The spell can be from any class's spell list (arcane or divine). Once a new spell is selected, it is forever added to your spell list and can be cast just like any other spell on your list.
Silent Spell: At 2nd level, you gain Silent Spell as a bonus feat.
Divination Spell Power Ex: At 3rd level, you gain a +1 bonus to your caster level when casting an arcane divination spell. This bonus improves to +2 at 6th level, and to +3 at 9th level.
This benefit comes at a cost: Your caster level for all other arcane spells is reduced by 1 at 3rd level. This reduction becomes 2 at 6th level and becomes 3 at 9th level. For example, a 4th-level rogue/1st-level sorcerer/6th-level unseen seer would have a caster level of 9th for her arcane divination spells, but only 5th for her nondivination arcane spells.
Guarded Mind Su: Any successful unseen seer must learn to protect herself from magic that would reveal her identity. At 5th level, you become protected by nondetection (as the spell, but with a permanent duration). For the purpose of divinations attempted against you, your caster level equals your character level.