Blue Team Difficulty:
As you enter the first room with enemies near the beginning of the level, sneak to the left, assassinate the grunt, and jump up to the vent with your partner. Inside the vent, one person takes the right turn, and one person continues straight. Each person can drop down the vents and onto an Elite. Once in position in the vents, together, countdown so you both assassinate your Elites at the same time. To assassinate an Elite, you must stealthily hit them from behind and hold the melee button. If both players assassinate their Elites at the same time the achievement will unlock. If not, reload last checkpoint and try again.