From a flavor standpoint, the Sidar are awesome. From a game standpoint, they are both underpowered and bland.
Let me say three things before I begin: (1) The mist is one of the most original and amazing features added by RiFE. I am blown away by the awesomeness of it. There are, however, a few problems, which I will address below. (2) I think that the immortality promotion change is not working, or if it is, it is not easy enough to see or understand when a unit becomes immortal for the turn. Lastly, (3) Rathus Denmora is an awesome machine of destruction. If he gets Orthus' Axe, the world belongs to the sidar.
OK, Now to my point: Remove the Sidar, and give the Mist mechanic to the Svaltalfar or the D'Tesh. Both civilizations are better than the Sidar at their own game: the recon line. In fact, that's the sidar's only game. In fact, their game really ends at the Poison tech, because everything else about the civilization is bland. Their early game is bland, their midgame rocks with assassins and Rathus, and their late game is as flavorless as lettuce.
One caveat- my favorite civ is the Hippus. I like to play a fast rushing civ, and the hippus do it in style. A lot of people complain they are bland. They are not bland in the slightest- they may be one- dimensional, and they may have an easily acessible focus, but they are fun. Very fun. And Magnadine is the most awesome hero in the game, despite what that flavortext guy says about his pony. Mounted mercs are awesome. They have flair and style, and they may be simple, but they are not bland. However:
The Sidar boil down to one tech. Poisons. Meanwhile, the Svart are rocking their +1 attack from turn one, and Thanatos is beating everyone at their own game. I love Thanatos, and after playing that civ, I see no reason to ever play the Sidar. So give the Mist to the legion, since they already have so many wonderful and surprisingly awesome things about them- why not add more?
Here's what is wrong with the Sidar, as I see it:
(1) the immortal promotion thing may be an awesome mechanic. I never saw a unit gain it when looking in mouseover. I had a level 25 ghost, and if never got it, then the mechanic is not working, or the chance is far, far too low.
(2) Rathus does not get the promotion that allows him to become immortal. He's like the king Ghost, bust the other Ghosts beat him at his own game.
(3) The Grey should be the ultimate watchers- they see all without being seen. That's their lore flavor, and that's what they should be like, in my mind. Sort of like the Dunedain (or whatever) from the Lord of the Rings- they watch all without taking an active interest unless things go to




. And everything is going to




in RiFE, so the Sidar must act. However, Thanatos does this better with fully invisible recon units. With a recon promotion. So do the Svarts.
(4) One leader no longer fits with the new mist mechanic. This is more of an annoyance, or maybe an oversight, or maybe could be a change. In any case, other civ's cities captured by the leader who has the (formerly called) tolerant trait retain their own civ's building capacity. This is great, because the sidar units are all so bland. However, it sucks because captured cities from other civs CANNOT use the Mist. Again, the mechanic is awesome. I think it's bad to have a leader who cannot use the only thing the sidar have going for them for a majority (at least to an aggressive player like me) of their cities.
(5) D'tesh has invisible great commanders. This is awesome. Very awesome. The sidar- well, they do not. I have a stack of 10 hidden ghosts and one, very visible, great commander. I also like the combat applications of the new great healer, casting heal on my ghosts. So it's two great people and a bunch of invisible units. Well, would be two great people, except they just die. (I know the worldspell into the mist would help here, but honestly, in my game, either I used it early without knowing, or was never able to actually use it, or couldn;t find it. In any case, it was never used).
(6) After poisons, you get those stupid and bland basic Shadows that everybody gets. You know what- the art in RiFE is amazing. Some of the units are stunning. The FFH2 and RiFE artists are awesome, and this is just bellyaching, but I hate the Shadow model as much as I hate the Paramander model, in general. But the poor Sidar, who even cares about their Shadows, because they can just stop at poisons. If they don't- barring religious heroes (which they will almost never get because of their tech priorities)- they get absolutely nothing unique.
When they used to be able to wane shades, the sidar could be nigh unstoppable end- game. They were like an avalanche; starting slowly, building momentum, and then crushing everything with a supercity. A supercity that, in RiFE, would be almost as good as the D'Tesh or Scion cities.
Ok so there's 6 points. It's not exactly material for the feedback thread. It is certainly a balance issue, however, because the Sidar are complete filler. They are not balanced against any of the powerhouse early game civs (Khazad, Hippus, Clan, and the incredibly broken archos), not balanced against any of the mid game civs, and have no real late game.
Want to make the Sidar on par with the Legion, the Scions, or the Archos? at level 6, all uints gain the blood of the phoenix promotion. They can die once and be resurrected. At level 12 (or 15, or whatever) They become truly immortal. There- now the sidar are balanced as overpoweredly as any of the other awesome, flavorful, detailed, and fun civs.
And one last thing- I have said it before and I can't say it enough- you have an awesome and incredibly talented team at work on this mod, and there is no game that gets even a tenth of the playtime as FFH2, and now RiFE. I love the "more is better philosophy," the innovative game mechanics, and the sheer brilliance that has gone into this mod. I'm looking forward to your work in Civ 5.