Orb of Shadow

The Orb of Shadow is a round black gem about the size of a baby's fist. When the appropriate command word is whispered, the orb summons a medium shadow elemental to do the weilder's bidding. The elemental remains for 30 minutes then vanishes, but can be called again immediately. If the elemental is killed, a new one can be called.
Strong Conjuration; CL 20th; Craft Wondrous Item, summon monster v; 180,000 gp.