Comments on the changes:
Time of Heroics - I really like the new Time of Heroics. Between Loxlorn Globe, and Mystic Feedback, every deck has a potential way to deal with it. It's an interesting card in the Celestial Imperium because they have no creatures that cost more than 4 flux. I do think that this tension should be stressed by making Time of Heroics cost 3IIX instead of 3IXX so that's it doesn't end up being the only Imperium card in a giant creature deck. (Side note: I really think that requiring double domain is an underutilized way of balancing cards. It's there, but not as much as it could/should be.)
Cathedral of Xosa - This was a much needed change. Still strong, much more fair.
Shield Generator - Another much needed change. Once again; still strong, much more fair.
Valley Fog - I think that this card might still be too good even at 2 domain. It's at it's strongest when it's played right after a domain building has been destroyed. The easiest ways to do this, Fissure and Sinkhole, also happen to cost 2 domain. I guess we'll find out. Oh, and I was hoping it would go to Sylvan
Knight of Celador - Now this is an interesting card. I like that it's not the usual give-control card. It will often give control of a very large amount of space, but it's limited by several things. It can be countered by changing the terrain, slowing down the creature, or moving/building a figure onto the controlled flux well. I really enjoy this card. It's unique, has amazing potential (Lesser Anemoi), and is, I believe, very fair due to the interesting ways to counter it.
Experience - Hmmm. I admit that I was mainly using Experience on my opponent's creatures to keep them dimmed for 3 rounds, and in that regard, I don't like the boost it received. However, it is more playable if used on your own creatures so I guess it's a good thing. I do think that it should cost 1IX instead of 1II though, as it's just not strong enough to be splashed into every creature deck like Training currently is. I just don't see a reason for the double domain requirement here. (Another side note: I'm really surprised that there's not a card that removes Sleep tokens. It would be a good fit thematically (Sound the Alarm!), and would make a lot of cards more appealing.)
) you should at least specificate which domain the stuff you are talking about belongs. In some of them it's obvious, but f.e. unless I use that Illiryon Lancer I can't have an idea where it is..