Earthmotes

Earthmotes are free-floating bits of landscape that defy gravity to hover in the sky. Despite their appearance, these islands in the sky are stable and durable. Earthmotes vary in size and altitude, and most are mostly level on top, resembling upside down mountains peaks.

    Effect: Earthmotes are excellent traveling fortresses and adventure sites.
    Usage: Use an earthmote as the fantastic site of an enemy base. Have the mote descend near the ground when the enemy attacks a settlement, making it susceptible to easy infiltration. After stopping the raiders, the characters can return to the earthmotes to gain access before it takes to the air. Be careful, however, if you don’t want the characters to have their own flying base. One way to avoid this is to have the earthmote lose its magic and crash to the ground, or go out of control, traveling in a random direction, once the enemies controlling it are defeated.

Published in Forgotten Realms Campaign Guide, page(s) 52.