I do not know who exactly come with this idea first...but this is my version (latest one, first is from more than a year back)
A new extra feature named COLLECTORS BOOK
This feature will enable 2 things:
1. u get a book where u can put your creatures: 1 page for creature and when u click on that page it will open all levels that creature has gone tru (creature requirements, description, etc. all should be available)
2. a new use for sacrificial altars, something i like to call IMMORTALIZE CREATURE, when u use this option it will fill a page in your book with the selected creature (max 1 specimen per creature) and by doing so it will take everything from that creature (days, xp, won fights, levels) making it a new born creature, also your character will loose half of the creature xp