Or you could just play cards like Ashling, the Extinguisher or Draugr Necromancer or Elusive Tormentor and get a 4/4 black creature for four mana with all upside and no drawbacks
Mortarion underwhelms likely because Toxrill, the Corrosive already exists
But if you find the well running a bit dry, there are also some big-mana card draw spells, like Finale of RevelationFinale of Revelation, Dig Through TimeDig Through Time, and Treasure CruiseTreasure Cruise
You could build around the legendary text or completely ignore it, though you'll probably want to lean on equipment for keywords like lifelink and deathtouch
Tevesh Szat, Doom of Fools wants to be left alone so you can get to his -10 "limit break" ability and gain control of all commanders in the game, whether they're on the field or not
All you have to do here is open up their menu and select the printing tool