Looked into that strange idol from Dragon Age 2.
It's the central figure of an altar... to the Old God Dumat. The hell is that doing in an ELVEN ruin?
Here's some stuff from the wiki about the altar
1) You pick up the side quest in.. Corypheus' prison.
2) The altar ITSELF is IN the Grey Warden's Prison Tower? How did anyone decide that having an old god ritual altar in the same place as a Tevinter magister's prison was a GOOD idea? For all we know, he was likely ecstatic to be so nearby.
3) The items required to complete the ritual are: Crown of Dumat, Dumat's Sacrificial Dagger, Dumat's Ritual Scroll, and the Sacred Urn of Dumat. All of these Old God Dumat items... located in the Gray Warden Prison Tower too.
4) Should you complete the altar's ritual, your journal updates to, "Sacrifices made at the altar of Dumat appear to have pleased the old god. The altar now appears dormant."
5) Your reward for doing the ritual is an accessory called, "Chain of the Penitent"
The important take away here is that this statue is representative of Dumat. It's not Elven. It's certainly not anything from the more modern, angular styles of Tevinter. What is an idol of Dumat doing in an Elven ruin? What purpose would there be to place that there? Why would the elves who built this place put idols to Dumat throughout the most holy, deep, and ancient portion of the tomb?
EDIT: Also, one of the Gray Wardens was clearly going to complete this ritual in Corypheus' prison. Why else would they have all the items there rather than destroying them or desecrating the altar themselves - like you can? Weirdness.
Andrastianism had not become popular by that point, so it's entirely possible that the Grey Wardens overseeing the construction of Corypheus's prison would still worship the Old Gods. It's doubtful they realized he was THE High Priest of Dumat.
Either that, or Corypheus's unconscious command of the Wardens coerced one into making a shrine.
It's bizarre that it seems connected to Dumat. Bioware manages to freak me out with architecture. I swear.
The Emerald Graves Knights' tomb reminds me of the Brecillian Ruins with their strange mixture of Tevene and Elvhen influences. Do we have any knowledge on when the tomb was built? It could be that it was started a very long time ago by the Arlathan elves or even before, and succeeding nations of elves living there have built more on top of it?
Still.
Bizarre.
At first when I saw the three weird statues over the dragons, I figured it had to be the Forgotten Ones. But Dumat.
But the Creators.
But Dumat.
But.
I.
DAMN YOU, GAIDER!