Named Character Spots: Each of the 50 named characters (Black Cat through X-23) has a dedicated spot. That spot captures all of that character's base cards, parallels, and any insert sets listed in the spot description. Check your spot description to see exactly which inserts are included — for example, Ghost Rider includes base/parallels, Fanfare, Topps Originals, and their Marvel Facsimile Auto.
All Other Characters — Alphabetical Group Spots: Characters without a named spot go to one of 16 alphabetical group spots (A through V-W). Each group spot captures all base cards, parallels, and character-specific inserts and autos for every character in that group.
Dedicated Insert Set Group Spots: Seven insert sets have their own dedicated group spots — every card in those sets goes there regardless of which characters appear: X-Force 35th Anniversary (all 10), Classic Comic Book Covers (all 10), Spider-Man Comic Excerpts (all 12), Cordially Invited (cards + autos), Meanwhile... (all 20), One World Under Doom (all 20), and Golden Anniversaries (all 10).
Marvel Facsimile Multi-Autograph Group Spots: Dual, Triple, and Quad Marvel Facsimile Autographs each have their own group spot. All cards in each tier go to that tier's spot regardless of which characters are on the card. Single-character Facsimile Autos go to the character's named or group spot instead.
Special Exclusive Group Spots: Six spots capture insert-exclusive characters and ultra-rare cards: Future Stars Exclusives A (Echo, Inari, Jia Jing, Myrddin), Future Stars Exclusives B (Peni Parker, Weapon VIII, Web-Weaver, Wonderful Wolverine), The Beyond Exclusives (Beyonder, Death, Maker, Molecule Man, Phoenix), All The One and Only 1/1s (Kang, Mighty Thor, Morbius, Sam Wilson, Union Jack), Stan Lee / Steve Ditko Cut Signatures (both 1/1 cut-signature cards), and All Comic Book Artist Autographs (all 35 artist autos).