+2 to the on the appropriate Art. page 118, Covenants.
I like it, especially that it's perilous.
How about a Signaficato? (Covenants, page 101)
The Giant's Goblet
On the coast of the Island, in the Regio, water flows into a large natural bowl, partially open to the ocean. The waters crash and swirl violently within the bowl. (Inspired by the Devil's Punchbowl, in Oregon.)
A magus must place himself inside the bowl, and allow himself to be battered by the waves. This allows them study Aquam, as if using vis, up to a level of 20. Characters can use one physical characteristic to reduce damage - roll against an Ease Factor of 12. Success indicates that the character is undamaged by the experience. Failure causes the magus to incur a medium wound, and a botch (players roll three botch dice) requires the character to roll on the Crisis table on page 170, although it does not end a Longevity Ritual. Using it more than once a year requires an Aging roll.
An earlier question on the main forum ([url]Build Point costs for Significatos?]) suggested that this should be about 20 BP
<I want a risk of injury for using it, but I'm not exactly sure how bad it should be.>