Darksteel Prowler

Indestructible
Artifact spells you cast cost {1} less to cast.
On occasion, a traveler may come across a drone
made of pure Madichen Darksteel. its a rare find,
but don't get too close. Darksteel is rare in these
times, and its likely something is actively stalking
it to harvest its metal. So be careful!
—Dr. Clearrunner.