Chance on hit

How can i do chance on hit spells like on DotA the phantom lancer has juxtapoze, i would realy like to now plz.

Check out Lord Vexorians Invx System. It uses a Chance on hit item - which of course could be modified to an ability or whatever.

http://www.wc3campaigns.com/showthre...409#post728409
look at the Lightning shield's code.