(We can always change the creative to shift a creature to a new creature type.) That got us to 74 creatures
While there have been a handful of spells with no mana cost (most with suspenda trend that Modern Horizons 2 continues in earnest), there has never in the history of the game been a "normal" creature with no mana cost
Sorcery Color tag templates(None) Revel in Riches Whenever a creature an opponent controls dies, create a Treasure token
Overlord of the Boilerbilges can either be a 6-mana 5/5 red creature that can remove something (or hit face) with its attack trigger, or just a burn spell for 4 mana
This is weak against an opponent with a lot of creatures on the battlefield but allows black to kill some creatures it otherwise would have trouble killing (like creatures with protection from black)
#1: WHEN TO MULLIGAN Veterans of lightning-fast eternal formats like to joke that the mulligan choice is their early game, but thats not really untrue for them, or for us