Assassins are equivalent to "thieves," as they use their speed to close in on an unsuspecting enemy and deal lethal damage. However, they are also "glass cannons" of sorts, as Tank or Damage Dealer players can swat them away with ease. Due to their high mobility and low health, they work best in solo modes. If this vibes with you, then you can get started with Assassins like Edgar, Leon, and Crow.