This is my take, and the TLDR for how you should build a mana base in BO1
The default level is tuned so you can win 75% of the time, Engelhard says, but you can tune it to be a bit harder. Turtle Team-Up costs $49.99 and includes: 4 Play Boosters 4 60-card decks themed around one of the four Turtles (includes cards from the main set) 1 Enemy deck featuring 39 new cards designed exclusively for Turtle Team-Up 6 Punch-out counter sheets 4 Deck boxes 1 Tutorial booklet
Such a set would brilliantly combine the flavor of Artifact subtypes, such as Books, and typal themes and mechanics, a popular theme Wizards of the Coast has used for multiple set designs
One of the most common uses of Empty the Warrens has been out of the sideboard of Storm decks looking to transition away from Grapeshots or Tendrils of Agony, into a backup plan capable of winning with Storm counts much lower (albeit, less reliably and less quickly)
6) Spinning Darkness Here's that alternate cost mechanic again, but this time it's based upon the graveyard instead of pitching cards from your hand