I don't know about patreon-specific content or teir-specific content, but I can maybe give teir suggestions? OwO
yer a bat, so maybe theme each teir of species of bats, either increasing in size or global population?
you could also do a gems/precious metals system; I've seen that a few times before
some others have just randomly named them furry puns x3

I'm thinking about using bat species as tier themes~