Setting is the Street map. Player's squad members limit is 4. Enemy squad is composed of 4 Ninjas, dressed in dark blue. They all have unlimited Chameleon trait, making them invisible. Enemies can use both duals and shotguns for primary weapons, but can't use custom weapons.
Use an Engineer with high damage rifle like the Crazy Badger or Iron Curtain, or use Explosive Weapons. When Ninjas come close to you they become visible for a second and that's how you can know where they are located. For easier battle, bring one Engineer/Mercenary with accurate Explosive weapon or Gunslinger with sniper, stay on the upper platforms and slowly take out Ninjas on the ground. You can also do this with MK32 or even better, it's custom version Bam Bam.
Normal (Level 7) - Ninja class if played for the first time. After that, random.
Hard (Level 17) - Random.
Insane (Level 32) - Evelynn