The Ever-Hungry Cloak

When the cloak is spread on a horizontal surface and the command "My, what big
teeth you have," is spoken, it opens a space
exactly like that formed by a portable hole:
6 feet in diameter, and 10 feet deep.
The hole closes when the cloak is picked up.
In addition, you gain +1 bonus to AC and Saving Throws while you wear this cloak.