Cards from previous sets like Mickey Mouse Steamboat Pilot, Pinocchio On the Run, and Cheshire Cat Always Grinning already had references to the Inklands in their flavor text
Some less powerful and unpopular Pokmon receive Rare Cards if they gain unique artwork
Key Spirit monsters that provide consistency include "Aratama", a monster searcher, "Nikitama" and "Sakitama", who grant extra Normal Summons to Spirits, and "Konohanasakuya", a Special Summon extender with a GY effect to let a Spirit monster stay on the field (by preventing its return-to-hand effect from activating)
Rafael was able to retain his soul after being defeated in a Seal of Orichalcos duel, he was able to see Duel Monster Spirits, and hes one of the select few who actually managed to defeat Yugi
The Return Of Hercules can easily be slotted into the deck without having it be stuck in your hand, and can offer versatility and niche gameplay interactions in the early to mid game
Because it was Black, this was not as important as Kavu Chameleon, which could become Black to prevent Black-based removal from taking it out