As for the card, I tried making it useful, yet not too overpowered for Magicians, which I know are powerful, so don't start on that whole "giving already powerful Decks more power" stuff, judge it without that attitude please
From there, it explodes into a myriad of other rarities, many focusing on distinct foiling patterns like Ultimate Rare (embossed foil), Ghost Rare (a 3D holographic image), Collector's Rare, the recent Quarter Century Secret Rare, and Platinum Secret Rare
R Rare Network Trap Hole X TRAP When your opponent Special Summons a monster(s) from the Main Deck or GY: Banish it face-down
Usually, sideboards need to reserve some space for Artifact, and Enchantment removal effects, but Boseiju allows such effects to be run in the main deck