Astasis

Astasis, also known as Arianka, is the god of law, or god of purity, and is rumored to be imprisoned by Tzeentch, waiting in a crystal coffin, waiting to be freed by crystal keys.

It is said that in Praag's darkest hour the goddess Arianka shall rise from the dead, and she shall smite the hordes of Chaos and drive them from this land for ever... There shall come a champion -- a man of Chaos, yet not of Chaos. Dark his deeds, but darker his doom! And he shall seek out the Crystal Keys and wrest them from the clutch of evil... ...And the Doomed One shall ride out from Praag, across the gushing Lynsk and thence into Norsca. And there, the forces of Chaos will close around him