I still don't like an additional prayer draining effect being available in PvP. It adds yet another method of getting you closer to being smited when getting tagged by multiple team members. I don't think corruption should work in dangerous PvP at all, or at a minimum have it not stack with smite somehow.
I'll get some clarification added on the spell as I don't believe it will stack, so you'd only have one instance of Corruption active.