New Redemption Grab Bag now includes an assortment of 500 cards from five (5) different expansion sets. Available at Cactus website.
Why not make it like Chopped?Establish a 'pantry' that can be used for each phase/contest, limiting it to sets (mostly likely) or some other condition. Anything in the 'pantry' can be used.Then, give the 'ingredients' in the basket: specific cards, identifiers, brigades, etc.Score on the overall 'taste' of the deck (power), 'presentation' (efficient design and play), and 'creativity' (how well they can incorporate the 'ingredients' and how central they are made to the deck).So you'd need some judges, but that could be fun.
So after one day we have 4 people who would compete, one judges, new ideas, and a deck idea. This is working out better than I could imagine.