Looking for clarification, hedge says you use the number of natural runes as your defense. I read this as the natural runes replace your current defense, rather than stack.
Example, if you armor up a darnati unit and have 3 green runes, you can choose to have your existing 2 armor (due to armor up), or 3 by tapping hedge. You do not get armor 4 for having the armor up plus natural runes, correct?