Unless I'm mistaken, Markov Baron is the only card with both madness and convoke, so when your mana is tapped out and you're faced with a Mind Rot or need to crack a blood token, three creatures can save this baron, it's sweet
Other subthemes in the deck: Bedecked Brokers feels very focused on the +1/+1 counters theme and most cards in the deck will synergize well by either distributing new counter types or proliferating
It shuts down a lot of junk, and makes it virtually impossible to block barring something like an indestructible defensive option
Talisman of Impulse
In Commander, you'll be able to make good use of Final Showdown, paying six to destroy all creatures, one more when there's something important you want to protect, and one more when you want to get rid of some pesky indestructible stuff too
Observing how others approach custom magic can lead you to adapt techniques for your own projects