The runes light up, and at first nothing happens. The skull then starts to shudder slightly, then twitch.
The skull then starts to bleed. Or wait, it's not blood. It's flesh. Flesh with eyes dotting the surface, swiveling around to look everywhere. The skull hovers off the ground slightly, and other bones start to connect to the skull. For instance, ribs and vertebrae give the construct four spider-like legs. Some large leg bones, a few joints, and some shards to form two long arms ending in sharp claws.
It still seems a bit unsteady on it's ribs, but it's lurching towards Mulberry, brandishing it's claws.