When this card is sent to the Graveyard: Target 1 monster in either player’s Graveyard, except "Tour Bus From the Underworld"; shuffle that target into the Deck.Right off the bat, it shows that it's meant to be used with Tour Guide. Not only that, but from what it's effect reads, it's assumed that one can get it's effect even when detached (similar to Dandylion needing to only reach the graveyard from anywhere). So since it's a searchable recycling tool, Tour Guide gets an even bigger buff. Not just because it can search for the Bus, but Bus then brings back any used card once it's sent to the graveyard.
Bring back to the deck any Dandylion, Tengu, perhaps a Gadget, or any useful monster you want back in the deck. Not only that, use that to bring back a used Tour Guide or Sangan for even more shenanigans.
But it also has it's offensive uses, which is what makes it really interesting. It returns a card in either player's grave, so you can take advantage of this to manipulate their graveyard to your advantage as well. Remove a Treeborn Frog, Necro Gardna, lower the Lightsworn count, perhaps remove that one key monster needed to summon BLS. Whatever you need gone, it solves quickly.
That's what makes this card so interesting, it's so versatile. You can either use it to reinforce your deck with a recycled monster, or turn the tables on your opponent by putting back in their deck a monster they need in the graveyard.
I fear what kind of mayhem this card will bring. Only time will tell...