It's a mighty fortress they've arrived to, all blood-rusted iron and seared pitted steel, and lesser devils on the ramparts, looking down at the newcomers with all the scorn their lesser kind can muster. It stands in the midst of a vast desolation, a volcanic desert with sand of iron and obsidian, from which, in the distance, not really all that far, bursts of hellfire constantly erupt from the ground; the firelight of the plane flickers, but has yet to go out for even a moment.
The magical Gate has taken them to before the physical sort of gate, polished and unblemished steel that stands in contrast to the rest of the scarred fortress.