8 part challenge, if you complete all 8, you'll get at least 100 books off your TBR. 

Note: Books you did not finish ABSOLUTELY COUNT for these challenges, since cleaning up your TBR is the whole point! However books cannot be counted for multiple parts of the challenge. 
 

Part 3 - Redundancy reduction 

Read 12 books on your TBR that have at least one other book on your TBR with a similar title or the same title. (Example: Brutal Ambition/Brutal Intentions/Brutal Obsession or Prey/Prey/Prey)

Alternative - books on your TBR with similar covers to other books on your TBR