The Assassin focuses on dealing two types of damage: Lightning and Void. Not all skills will have an associated elemental damage, but those that do will have their damage increased with the selection of the right items; building a focus around these damage types is advantageous in the long run, especially as you get to the end-game dungeons.
For party play, the Assassin takes on the role of a strong damage dealer, able to easily handle the weaker one-off enemies, or work in concert with the Kung Fu Master or Blade Master to whittle down a Boss Monster’s health. The Assassin must be careful to manage their threat, as attracting the attention (and damage) of enemies can leave the Assassin struggling to remain alive, then you may need Blade & Soul Power Leveling and greatly reduce their effectiveness.
In Arena PvP, the Assassin’s strength in precision attacks and movements comes into full play. While they’re normally unable to execute the full combos that would get them through any PvE situation, disciplined Assassins know how to take control of any situation by effectively using their Stealth and confusion mechanics, or just by taking advantage of opportune moments.