mtg secret lair cards x God of War: Norse Foil Edition Warren Mahy Magic The Gathering, Secret Lair:

A creatures converted mana cost is determined solely by the mana symbols printed in its upper right corner (unless that creature is the back face of a double-faced card, is a melded permanent, or is copying something else

It stops people formulating long term plans, leaves reactionary interaction stranded in exile, and is a pretty reasonable piece of lite stax

I believe the solution has already been prototyped and road-tested by two of Commanders less famous cousins: Canadian Highlander and 7-Point Highlander

As you can see, this is drawing one card per creature spell cast, typically for free, although the Lifecrafter's Bestiary costs mana