Espionage

Espionage is conducted by assigning a with the appropriate skill to a spy mission against an empire you have made contact with. A full list of spy skills can be found in the Leader Secondary Skill list.

Both ship and colony leaders may gain spy skills, which can be used by selecting at the bottom of their info card on the Leaders Screen. On the Mission Screen, you will be presented with a list of those available to that leader as well as their targets which may be a particular system or the empire itself depending on the type. Set Up Time is how long it will take to completely the mission, and Detection Change is the likelihood of the target empire becoming aware of the action after it has completed.

Spy missions always succeed--detection only results in a deterioration in diplomatic relations. At higher skill levels, there is a chance of framing another empire for the action.

Missions can be canceled at any time, so they can be a handy way to avoid the unassigned malus for leaders you have no colonies or ships available for even if you don't really wish to engage in espionage with them--simply assign them, then cancel the mission before it completes.

Spy Mission Types
targets an empire and provides information on it.

steals a technology from the rival from a list of those 1 level below, equal to, or above your own max research level in each tech tree.

lowers the opinion of a rival's leader; at -10 opinion they will defect and become available for your to hire.

allows destroying a military installation or ship in the selected system.

Espionage Tactics
Since espionage always succeeds, the most important modifiers are those that decrease the number of turns to set up your own missions and increase the number for your rivals, though modifiers to detection and framing can also be important.

The empire building adds 20 turns to rival setup time as well as increasing detection chance and providing an immediate bonus to your leader's opinions, making them more resistant to desertion.

The empire building reduces your own setup time by 5 turns in addition to reducing detection chance and attracting spy leaders or increasing the skills of your current spies.

Some leader traits such as and  provide bonuses or penalties to particular leaders.

The Elusive, Suspicious, and Easily Seen racial traits each provide bonuses or maluses to spying.

The best defense against Pys-Ops is keeping your leaders happy--an individual mission can only lower their opinion by 8 with the most skilled spy.

Empires are less likely to engage in spy missions against you if you have good relations with them.

A further defense against spying is that since there are a limited number of leaders in the galaxy, the more you have, the less your rivals can have. Try to hire every leader you can on the turn before they leave, especially if they have spy skills--if you don't need them, you can immediately assigned them to a mission. Engage in Psy-Ops yourself to convert their leaders to your cause. If a particular empire is a particular annoyance, it may be time to their colonies to steal their leaders--or to liberate their entire empire from such a duplicitous leader.