How to get "Dark Ritual" to Cast on Non-Undead units as well?

[Brash]

I'm trying to figure out how to get the spell ability for lich named "Dark Ritual" to cast on other units besides just undead ones. How is this done? i've looked in the object properties and the gameplay constants and i dont see anything about this.

 

[Jaakko]

Go to object editor and find this spell and change the allowed targets in the right field.