Walter’s Rounds(modification)

[TrinketAddicted]

I was hoping to get some information from other people about topics that bothers me.
I was doing some modification to the Walter's rounds, I was fine with changing it recepies and changing it damage, but how do I change planar damage or how do I add it to the rounds, and also what about AOE damage and can I change it radius? I'm not sure if this is a thing, but is there is any lists that can show all of the function that are explained and can be applied to the item/character?

[TrinketAddicted]

anyone?(I found files, but still can't understand how to work with aoe and planar damage)