Several Mountainfolk creatures are now, after the domain requirement changes, somewhat overpowered:

GLorn Airship- Costs 3 flux to play (after 3 control), has 5 toughness, and 4 attack. Additionally it can't melee. So now what you have is a flying 4/5 creature that can't be attacked by ground creatures, can soak most ranged attacks, and costs 3 flux to play. It should be looked at, definitely take its toughness down a point or two, and probably it's attack. It's a floating gas bag: it shouldn't be that tough to kill

Epic Veteran/Hadith- Both are reasonably well balanced cost wise for as hard as they hit, but they're overly tough to kill, especially Hadith with his Battle Ready. Suggest taking them down 1 HP each, and taking away Hadith's battle ready (but keeping his ability to bestow it on other creatures)

Bilgrim's FIrst Prototype- Needs to start with 1 less speed. Otherwise, good.

Most of these wouldn't be huge issues if you were able to control MF creatures with enchantments or buff your own with the same. However, MF is currently the faction with the best arsenal of permanent eleimination: Negate (1 flux), Disenchant (3 flux), Sinkhole (sacrifice + 3 flux), and Hex Chaser, which is a great card in and of itself.

Basically, until there is a way to counter the huge disenchant/direct damage ability of MF, it's too advantageous to allow them to play such huge HP creatures under the new rules.

It sounds like you need to change your strategy rather than complain about cards. You cite 4/7 of the 3-domain MF cards and yet you mention nothing of the other races' 3-domain cards which are just as (if not more) powerful.

I have to laugh that you complain about Glorn Airship first. Sure it's only 3 flux, but you fail to mention that it has movement 2 and can't defend itself against aloft. I.e. if you have ANY aloft it'll be gone in a few turns and with the slow speed, any non-stationary target can get out of the way easily. I have two of them, I've never played any of them in a non-sealed deck because they're dead before they do anything.

Epic and Hadth are tough, fine. That's sort of the theme for MF.. Try saving your ascent/entangle/lysis/etc for something other than wimps.

Prototype goes to 3 speed after one round of melee attacks, which is the average amount. Another attack or defense and it almost definitely is out for a turn. They attack quick and wither quick, weenie them and they won't be able to fight back.

You also fail to mention that negate gives you back all your flux so you've got a slight bump in the road but can still go about your business (while the caster is down a flux). Disenchant costs as much as a creature (and more than over half the enchants in the game). They trade one of my cards for one of your cards, and the subject they're cast on almost always comes out better off in terms of flux. They also clog the MF player's hand usually for long amounts of time and require a flux "padding" to always be in the ready. What's the problem here, exactly?

It's pretty clear you've never played a MF deck. There is almost zero creature control so you have to rely on big guys and negates/disenchants if you hope to have a chance. Fine, things are slightly different now with splashing but the basics remain the same.

In limited play, one of the best control decks I've ever had was MF. I had 2 avalanche, 4 manipulate, 3 horns to hide, 1 negate, 1 training... I splashed MF spells with sylvan creatures and shazam! Glory was achieved. I don't think MF has a control spell deficiency... I just think they're a little more subtle than the other domains.