SILENT BUT DEADLY
Kill 7 opponents from behind in a row without being spotted
Halo 2 HI BEN – Achievement Guide
Complete Skull and Terminal CHECKLIST(Halo 1-4 / Google Docs)
Mission: Cairo Station
Early in the mission you will come to a hangar that is being breached by enemies. Shoot at the tube they are coming in. The first wave of enemies will get stuck in the geometry. Once the second wave of enemies comes in, they will get pushed out. That’s when you want to start shooting again. Since they are not in the Mission area yet it counts as a stealth kill and the achievement will pop.