As I've been leveling up my accounts, I've found I really wanted this chart, so I thought I would make one for you. As monsters level up, they gain abilities, and some of these are extremely important - attack for Swamp Thing and Goblin Shaman, Heal for Flesh Golem, Blast for Fire Demon, and so on. Knowing where those abilities come in is very important for deciding how to level up your teams. Since leveling up always begins with your summoner, I've decided to group new abilities by rare summoner level. To keep this from being huge, I'll split it into separate posts by splinter.
Neutrals get almost all of their abilities from the beginning. Only six of sixteen cards see significant improvements with leveling, and they're focused on Levels 3 and 5. Apart from the Legendaries, Neutrals are largely about single abilities and stats.