Well, the decks creator thought Phyrexian Plaguelord looked like Dwayne The Rock Johnson, and the millions refer to his millions of fans, or the millions of creatures you summon with Deranged Hermit
Remember you can use the old Sneak Attack trick by activating the ability during your opponents end step to keep that creature around until the end of your turn
Belle comes back with a few alternative versions, including an Enchanted version, and a Quest promos available in a number of activations hosted by Ravensburger and partners while supplies last
I can see it put in a lot of work in decks that focus on making artifact tokens - Tivit, Seller of Secrets or Eloise, Nephalia Sleuth now allow you to sacrifice your clues for the same amount of mana but gain extra benefits for example
Slaying Mantis fights each creature one-on-one in a handicap match
Being able to see your next card draw every turn is a great asset, but being able to cheat out creatures from the top of your library or from your hand, bypassing counterspells, is incredible