i personally think guardian is fine, I like to use it by putting it near the enemy king, and having it swap to protect a strong unit who can then kill the king.
I like the null idea, it adds a unique unit who i can definitely make a stupid army with.
I think the guardian change was intended as some form of pseudo-buff, but considering the other changes maybe it isn't needed?
glad to have you here btw
going to take a bit of getting used to this forum but it will work out. Glad to see you're back!