Okay, so I got the idea for this when I saw this beaut https://discord.com/channels/278418306271281154/613021811424100372/1170922595500183686 & I thought "Hey that's nice, but wait a sec. If something is set to use the character stat, then you'll be forced to make a stat that every character is gonna have, and you might not want that sometimes, in fact, I don't want that right now. Thankfully, we have properties, however, they can't be used as a cost."
So my suggestion is for the ability to use Global, Player, Item, and Self properties as costs as well. Global and Player properties at the very least. It'd allow for a lot of potential.