Thank you to everyone for the replies. I believe some changes are in order.
Hybrid cards will be allowed. My objective was complete purity, but I can understand that this would equate to a harsh ban list. I will also drop the maximum player count to 16, and an intermission will occur after the quarterfinals. If attendance is too low, I will reschedule for next week and set a better time if necessary.
Generally I post 1-2 weeks in advance of an event, but I took two days longer than planned to make the announcement, and I was uncertain if the pauper league was decided to be Fridays for sure, yet. I can write more when I get home from work, and thank you for the constructive feedback.