help with (passive) chain lightning on item

[Ordonian]

How can I make a item that will cast chain lightning on striking? Not all the time either, just every once in a while. For example, a 15% chance to cast chain lightning on striking. If anybody could help that would be great

 

[QueloR]

If I'm right you can make a custom item based on lightning orb (new) and modify the effect that it triggers (default purge(2)) and change it to an chain lightning.

 

[Ordonian]

Thanks, I tried it and it works.