First, a worm gem is crafted using 3 worm hearts. Ducio can do this, and says it’s simple once you know how, but doesn’t elaborate. After the gem is created, you must cast "Create Soul Prism", which turns the worm gem into an empty soul prism. A soul prism that captures the soul of a once-living warrior is called a living gem, which is what grants an automaton 'true life'.