Preface: There's a lot of work for this and might only get started around the 3-year mark of leaving LINE, if not later... Beyond what's already there (or will be.) Following the absolute 100% completion of the Main Story, the character specific Origin Story, and the acquisition + evolution of all available character cards [corresponding to the chosen Origin Story] to gold, i suggest the following: Master difficulty Origin Story, with no other characters required but optional. I.e. no "Only Solo Painwheel" node in a Big Band Origin Story. A new and extensive Master difficulty mode designed specifically to challenge each gold tier card via trials. Since only those specific cards would be allowed on the stage, other characters [any tier] with support signature abilities are allowed on the team but will be kept locked away via a permanent Disable Tag Ins debuff. For certain cards, certain support characters may not even be allowed. As Sekhmet once said, "You serve me!" Upon the absolute 100% completion of those 2 by the player, they are rewarded with the Sparring Partner card, platinum tier (according to rumors.) Sparring Partner Cards! If 1 is earned for each set of trials per card completed: All Sparring Partner cards stack in the collection and count as 1 space taken per character from total inventory. E.g. you got 6 "Sparring Partner" Cerebellas & 3 "Sparring Partner" Beowulves in inventory, they only take up 2 visual slots and count as 2 in inventory. They can be sacrificed into maxed gold/tier above gold cards of the corresponding character to bump their stats of the player's choice, please. Limited availability: 24 per character [25 for Big Band] Limited number of sacrifices allowed for each gold/tier above gold card 14 Sparring Partner cards can be merged to create the playable "Sparring Partner" variant. More info in following list ↓↓↓ if only 1 is earned for total completion: The Sparring Partner's SA can be mixed and matched from all available SA components from that specific character according to the player's preference. Choose wisely, changing it could cost hella theonite. To prevent overly powerful SA pairs, the SAs can be separated into 2 lists where the player can choose 1 from each list or on a case by case basis where selecting 1 will fade out those that would make it too powerful. The base stats could also depend on the SA pair chosen. The Sparring Partner card cannot be leveled up if the Signature Ability hasn't been set yet. Sparring Partners are not allowed on defense teams. Feedback welcome! Goal of this was to provide endgame content ideas for players who are primarily interested in a select few characters and don't want to go through the arduous task of leveling up every other single character given beyond what's required, along with a useful "Sparring Partner" variant as a reward.