The thing that Rogue and the Doctor trapped the Chuldur on in "Rogue"? Huge triangle. We may have seen Sutekh in satanic form. One other thing noted in "Pyramids of Mars" about Sutekh: The ...

Sutekh is an old enemy of the Doctor's who first appeared in 1974's "Pyramid of Mars." Then, as now, he called himself the god of death, and his deepest desire was to destroy the entire universe.

Beneath a pyramid, the last of the Osirans — Sutekh the Destroyer — waits to be freed, to at long last bring his gift of death to all who live.

Russell's bare-faced lie was all a ruse to preserve one of the greatest cliffhangers in recent years, as “The One Who Waits” was finally unmasked and Sutekh ... of the Pyramids of Mars callbac ...