Complete Image is a complicated card with a simple purpose: it is a win condition that allows you to flatline the runner if you know the identity of every card in the grip.
Before I get into the ins and outs of Complete Image's primary feature, a few things to note:
Complete Image is a Terminal operation, meaning that there is no way to use two in one turn, or deal other damage after the effect resolves.
It can only be used when the runner has at least 3 agenda points, which can be relevant and allows some counterplay on the part of the runner--you don't have to be worried about how many cards are in your grip early in the game.
It has a trash cost of 2, meaning that it is vulnerable in Central Servers.
Complete Image always does 1 net damage at least, meaning it can be used as an expensive Neural EMP if need be.
Complete Image's primary feature is a frightening and exciting recursive net damage cascade; if you know every card in the runner’s grip, the chances of flatlining the runner are as follows:
• 5 cards: ~1% chance (1/5 * 1/4 * 1/3 * 1/2 * 1)
• 4 cards: ~4% chance (1/4 * 1/3 * 1/2 * 1)
• 3 cards: ~17% chance (1/3 * 1/2 * 1)
• 2 cards: 50% chance (1/2 * 1)
• 1 card: 100% chance
• 0 cards: 100% chance
Two things become apparent looking at these odds: 1) while similar to Neural EMP, Complete Image also lets you flatline the runner if they have just one card in the grip, and 2) your chances of flatlining the runner increase drastically for every card that is missing from the grip. You are 5x more likely to flatline the runner if they have 4 cards in hand instead of 5. And if they have 3 cards, you are 20x more likely to flatline the runner than if they had 5 cards in hand. This means that every value damage you can do before firing the Complete Image greatly increases your chances of winning the game. Using Neural EMP, Bio-Ethics Association, or Ronin are more or less reliable ways to line up your shot.
However, again this all requires perfect knowledge of the Runner’s Grip. To get this knowledge, a few options are available. Jinteki IDs such as Hyoubu Institute, or more reliably in my opinion, Chronos Protocol, have built-in ways to gather this information. Several NBN cards, such as Salem's Hospitality, Peeping Tom, and Standard Procedure also allow you to gain the information necessary to land the kill.
Notably, Standard Procedure, Neural EMP, and Complete Image all require a run to have been made last turn. So using these cards all in one turn is one way to land the Complete Image.
To counteract Complete Image, runners can trash it when they see it, they can try to stay below three agenda points, and they can keep their hand size as large as possible. In addition, a single net damage prevention card can stop the entire process in its tracks.
Complete Image is a powerful win condition card that can allow you to simply end the runner with a bit of luck and knowledge of their hand. Landing the Complete Image can be tricky, but watching a lucky net damage cascade flatline a runner with a full grip is certainly a memorable moment.