Poison attack splashes (no triggers)

[darkrider]

i want to make an item that when you hold it your attack splashes to nearby enemies of the target also poisoning them.

i made it by adding acid bomb to an orb of lightning modified ability and adding it to my item... everything works fine *EXCEPT* for that blizzard bug that if you dont order your unit to attack (it auto attacks by itself) the orb of lightning wont work, as you may know

any idea on how to solve this, or make the ability in a different way?