Chloe grabs Marty's hand in hers, and with her other hand, slots the key into a hole exactly the same size as itself, like putting a disk into a computer. Immediately, a blinding light erupts from the surface of the altar, surrounding them with an almost liquid white glow that shimmers and pulses, and then they're in a tunnel of energy, swirling blue and red and yellow, moving swiftly even though there's no physical sensation of going anywhere.

When it ends, they're standing in a room of ice and crystal (http://images.wikia.com/smallville/images/8/8b/Arrivalhr065.jpg), massive spires towering overhead. But where the Fortress would normally be glowing white and blue, it's red, almost the color of blood, the spires dark at the core. It's shadowy, spooky, and something is clearly wrong.