Wondrous Figurine (Obsidian Steed)

This sinister-looking black statuette resembles a horse rearing up on its hind legs.

When activated, this figurine becomes a Nightmare.

It can be called upon once per week for up to 24 hours, though it won't use Interplanar Teleport or its other abilities on behalf of its rider.

Although evil, it allows itself to be ridden by creatures of any alignment, although if a good creature mounts it, the rider must attempt a DC 3 flat check. On a failure, the nightmare uses Interplanar Teleport to take the rider to a random location in the Abyss, where it promptly returns to statue form, stranding its rider in that nightmarish place.