Something pearlescent to represent light refracting from their armor for the plate. Some green/blue metallic for the scales. Light blue for the cloth. I am stumped on the robes though. White, maybe?
On another note. I think this has probably been mentioned before, but...
What we have seen thus far is basic infantry, cavalry, archers and the Light of Eltharion. These are the generic, non-elemental models.
Then come the stone mage, hammerers and the battle bovines. Mountain.
Do you think that the rest of the elements will follow the same pattern? That being one Special unit (hammerers), one hero (mage) and one big/special model (battle cows)?
So you fill your battleline troops with the generics, and then spice it up with an elemental unit or two.
This way, we can still see one more elemental aspect released (that's 3 warscrolls, not unreasonable), maybe more.
Teclis is an exception, as he has mastered (and therefore encompases) all the elements. He will be the only God tier release (Tyrion will just steal some of his spotlight).
I like the elegance of it. This way we could be getting a min. of 3 releases and a max. of 9.
Just wanted to chip in on the speculation.