


All it takes is for a single player being cautious to test the cleansed vis prava with a minor spell to discover that it became vis sordida (that +5 instead of +2 is rather noticeable), or even looking for a character with decent ranks of Sense Unholiness to take a look, and then triple applications will become the norm. Yeah, it doesn't operate in that it takes up to three applications to fully cleanse the infernal vis. So a character using this spell is not supposed to know how it really works - and if her player games the system, he should not blame troupe or SG for the outcome. Tha rulez on RoP:TI p.122 specify, that Cleanse the Verminous Vis "does not operate quite how the Venatores think that it does". Or, if you want to stay within the rules, arbitrarily have a powerful demon sneak into the magus's lab and mess with their lab so the spell only 'looks' like it works. Yes, the GM is free to change the rules on the player without warning. Cleanse the Verminous Vis remains an option to keep it around.
