After continuing to play, I noticed a few bugs (sorry if these are re-posts.  Have not seen them before):

growth/giant form not working on large units (anything over ).  It works great on Champions and , though.  I know it would make a   very powerful, but if that is why it cannot be used, it should be spelled out in the spell description.

Cannot build on their land after defeating elemental lords (old gods) - might need  to "revive" the land.  If so, the revival spells are not very well spelled out - not sure what "revive the land" means.  

Also, after reaching V in Earth magic, I still do not have either of the two "revive the land" spells.