As you move toward the planar crystal, it begins to drift away from you toward the gateway.
You follow it, but it floats higher and higher. Almost magnetically attracted, it speeds up out of your reach and clinks into place at the top of the arch. As soon as it does, a sound resonates through the chamber, shaking the stone floor.
VOOOOOOM.
Balgor jumps and turns around. The two of you watch the gateway. A light grows brighter and brighter in the center, swirling like a whirlpool. You can see the faintest of outlines of a city, flickering in and out of view.
"By Palor's Beard..." Balgor exclaims quietly, approaching the portal.
He tentatively reaches a hand forward, and you see it touch a flat surface--as if an invisible wall is preventing his entry. His shoulders relax, and he bows his head.
"I'm so close...so close. I haven't felt hope like this in a millennia."
He looks up at the crystal, in the indent of rock at the top of the arch, then back to the swirling lights in the blackness.
"If only I had the remaining pieces, I'm certain then....then I could go home."