Jungle · Assassin · also roam
Saber
the Wandering Sword
Locks onto one target with Triple Sweep and deletes them. Simple assassin.
Should you main Saber?
Saber is a jungle hero rated easy to pick up, with range: melee, mobility: dashes all over, crowd control: little, damage style: burst, power spike: early game.
Saber is a good first hero: the kit works without much practice, so you can focus on game sense.