This conversion was accomplished using a Chaos Cultist. The head is from Maxmini. I created the staff using some styrene rod, the tip of a glue applicator, and a the Forgeworld icon shown below.
The head of the staff was created by molding and casting two copies of the Forgeworld Inquisition icon. They were then trimmed down to the icon only and glued back to back. The purity seals are also green stuff.
The original model used was the cultist pictured in the lower left of the box artwork shown below.