Play as Assassin
To unlock Assassin, you must already have weapon master mode completed once.
In chapter 8, complete the stage "Crystal Mine", in both the extra and normal missions.
This will open up a path to sub-chapter 3. The second mission in sub-chapter 3 is called "Castle Of The Damned".
Since you hav already completed the game once, you will have an extra mission for "Castle Of The Damned",
in which your opponents are faster. You must defeat the enemies, who are (in this order):
Voldo, Ivy, Yoshimitsu, Taki, and Assassin. Complete the level to unlock Assassin.
He is available in all two player modes except for arcade and extra arcade.
He is also available in practice and extra practice modes. Assassin has six costumes to choose from,
and some of the best combo and juggling moves in the game.

beet the a lvl where u r poisoned note: best with night mare and the soul edge growth