Solitude
Baz'Auran took a moment to consider his second-eldest son before answering, giving the others a chance to add their own sentiments to the question. When none were forthcoming, he gestured to the ceiling, where the Disk suddenly appeared writ large.
"A pertinent question, Faden, yet one with a simple answer. With my blessing, a spirit might endure an eternity on the Disk, but such an existence would be against their nature. The Disk is raw, material reality - spirits are more ethereal beings. I do not send them to the surface without good cause, and in this case their coming would mitigate the challenge set before you. This test is one of your sparks alone, and while a proper locale for each of your challenges shall be chosen, that is the last help you will receive until your ascension is complete."