kit pvp help

Im doing a kit pvp code for a server, and i need 2 helps
1) how i made an eventhandler to when i do i hit in a guy, the guy get a poison effect?
2) how i made this eventhandler only work when a guy put a command

sorry for bad english and hellp

 

On the event check if the guys name is in the list, then poison the enemy.
Put the guys name in a list when us uses a command.

 

Ultimate_n00b
i understand, but what is the CODE?

 

.. you only came to ask for code? Why not make it yourself?

 

but i dont know what the code i put, victim.getpotion?

 

victim.addPotionEffect(new PotionEffect(PotionEffectType.POISON), duration)

 

@boss86731 thanks so much
@Ultimate_n00b Thanks soo much too
a little help, the code ent.addPotionEffect(new PotionEffect(PotionEffectType.POISON, 100, 1)); works too?