ad arbitrium censoris
For each oath and mark the Censor-Mage collects, a measure of lifeforce may be called upon by the collector. An oath can only be made by a signitor free of mind. A Censor-Mage may not lie about the ramifications of signing. Each score of signators will result in another level of lifeforce. If the Censor-Mage calls upon the lifeforce it is pulled equally and permanently from that score of signitors. This accumulation of lifeforce lasts only one lustrum (5 years) at which point all obligations become null and void.
Thanks to mike in the comments to the last post for the idea. So, your MU goes around signing people up to your worldview/quest goals. They sign on and you get some hitpoints you can burn through in reaching those goals. I'm thinking 1 hit point for 20 every signitors. That way you sign up one serf and it's in his best interest to try and help you sign up 19 other folks to share the burden of that one hit point permamnently lost. The hope is that the difficulty of getting someone to offer you some of their hitpoints will balance the powerful gain of hitpoints.
Using the hitpoints logistically I imagine being similar to splintering shields-- you get hit and you can decide to burn up one of these communal hit points or not.
With spells like this, that incorporate costs or difficult choices within them, I have no clue what level to make them. What level would you make this?