Like every other side mission, this mission is played on Street. You go against a group of enemy Snipers. From the beginning enemies are winning with 12 kills and that makes the survival harder. You are invisible. You can walk past the enemies and they won't notice. But if you fire they can notice you, and kill you quickly because they use highly accurate and powerful Rehabs. All enemies have Rehab primaries and Jericho secondaries. Also, whatever you do, do not use a ninja for this level, because their normal chameleon trait will still effect you.
Play as the Engineer or Mercenary with an explosive weapon and stay in the corner and fire rockets/grenades to the snipers. You can also use your invisibility to get between group of soldiers and blow yourself up. That way you die much but it's a cheap way to win the mission. You can also crouch down under barriers as Snipers cannot target you when on the ground. Avoid close combat, unless you have a high level melee weapon. You can play as Juggernaut who has Flame Armor killstreak. Because you are invisible, your fiery shield is invisible too. Just walk near enemies and they won't notice you and will quickly be ignited. However, the problem is weapon if you play with Juggernaut. All weapons he uses are close range. But R870 and Defriender shotguns have longer range so that is the best choice. An Elite with an DSR1 camping in the corner is also a good solution, too. Also, your usually killed instantly when you first spawn because you don't automatically become invisible when the team deathmatch starts.
Normal difficulty: Sniper Class
Without the invisibility, playing this level will literally be impossible, because you won't last very long before being shot in the head and killed instantly.