Out of curiosity I wanted to find out how much likelier an object becomes if you, say, double the rarity value (turns out it's twice as likely, how nice). To do this I used the stats generator and tracked the frequency of items as I mucked with their rarities. The results for potions are below.
Luckily the curves look mostly linear (they'd probably be more linear if I actually did a reasonable number of sims, but I'm lazy) I'll probably have more to say on this later, but for now, I'll attach a pretty plot and link you to the raw data.
raw data
Luckily the curves look mostly linear (they'd probably be more linear if I actually did a reasonable number of sims, but I'm lazy) I'll probably have more to say on this later, but for now, I'll attach a pretty plot and link you to the raw data.
raw data