Going back to the Tomb is fine, but we're getting close to the point of diminishing returns.
I too would like to see what's up with the Killing Frost. Although if it were to somehow become de-Anubisized, I believe that ENL would somehow sense that, or would at least be able to check by trying to summon it again. If Anubis did, as James suggested, take on the qualities of the beings he zapped, maybe ENL would have some kind of connection with Anubis. (Like in a recent episode of Avengers: Earth's Mightiest Heroes where Absorbing Man touched Mjolnir, absorbing its properties, and Thor was able to then control Absorbing Man the way he controls Mjolnir.) I doubt we would be that lucky, but maybe it's worth a shot.
I think we should ask Ontussa whether or not the Caged One can actually help us and/or hurt us. If he can't help us or hurt us, the rest of it doesn't matter. But if either one of those is true, we probably want some more information on him: in what way(s) can he help us/hurt us, who is he/she/it, is he really telling the truth, or if not, what is the truth.
If we don't want to go back there, I think another cool place to check out would be that place that I think Rakotis is from/works at/etc. What is that, the Citadel of Fire? (I saw that name on the updated map, and I think that's what that place is, right?)