I miss having a big variety of different CRs for each monster, with not only different hp and AC but different variant abilities. I know I can create monsters myself but I need a greater variety. I have a player that has already memorized the stats for everything in the Monster Manual. I know I can reskin monsters but I can't wait for a Monster Manual 2, 3, 4 etc. so I can mix and match and replace monsters in adventures, use orc paladins, goblin wizards, legendary hydras, elite medusas, etc. right out of a book with no prep time. Even better I'd love a DM's Tool software where I can easily grab a monster from the Monster Manual and at the click of a button get a higher or lower CR version of it, or add a template to it and see its new CR.