For example, you can't cast a creature card with mayhem you couldn't normally cast during an opponent's turn, even if you discard that card during an opponent's turn
Until your next end step, you may play one of those cards
Likewise, their ability triggers not in the Upkeep nor Endstep, but at the beginning of the combat phase, the extra card draw and the token give us a variety of options to plan our actions in combat
What really makes an Edgar Markov deck pop, though, is if you play him with mass land destruction, such as Ravages of War or Armageddon, resetting the board on turn four, while everyone else is trying to set themselves up with extra lands
I have a system that works for me that uses binders for holding the cards I use often, deck boxes for holding my decks, and long cardboard boxes for the bulk that gets used less frequently
On their own, flying creature cards are already a real threat to players who don't have creatures with the reach ability in their decks