The Angel Cartel are a pirate faction found throughout Minmatar space, considered to be the most powerful and dangerous criminal organization in New Eden. They pilot ships that are thought to be based on ancient Jovian design, using target painters that increase your signature radius.
Combat sites in Eve Online can be divided into three categories.
Combat anomalies appear as green on your probe scanner window, allowing you warp to them immediately. All combat anomalies have a small chance of spawning a faction NPC, and many have a small chance of escalating to a D.E.D. rated combat signature.
Combat signatures must be probed down before you can warp to them. All D.E.D. rated combat signatures consist of multiple rooms, and have at least one special NPC or structure that has a chance to drop deadspace modules or blueprint copies for pirate faction ships.
Unrated combat signatures have a faction NPC or structure that have a chance of escalating to a four-part expedition. Each stage of the expedition has a chance of spawning a faction NPC, and a chance of continuing to the next stage of the escalation. The final stage of most expeditions will be in a low-security system, and will have a special NPC or structure that has a chance of dropping deadspace modules or blueprint copies for pirate faction ships.