I thought this would be a better place to put this rather than in the general comments section, given the extensive nature of my feedback, but I really do quite like the update! Overall, it turned what was basically a novelty mod with fairly uninspired gameplay into something more on the order of mechanical depth of the base characters.

Feedback, in no particular order:
>The benefit of upgrading individual cards feels wildly unbalanced, but generally undertuned, if anything. I'm not sure there are any cards that get a reduced energy cost from being upgraded at all. Please consider adding this to at least a couple of cards, especially for a mod that adds relics which can conceivably populate the boss drop table to the point where you can't get a vital energy-producing relic.
>The Starting Buxom UI element doesn't always seem to update with my actual starting Buxom, and starting Buxom doesn't seem to be reflected when the sprite is displayed during shopping (I could see this being an engine limitation, but it's a little disappointing either way).
>Having gone on an extensive endless run, I have not seen any of the custom events even once; maybe raising their probabilities would be a good idea?
>Thank you for adding a way to increase base Buxom, btw! That was my biggest ask, and it's been delivered on. Perma-Growth potion is wonderful, too. I would love it if there was a Relic that continually increased base Buxom, though!
>A Power card that grants continual turn-by-turn growth would be amazing, too.
>Unfortunately, it's often difficult to see the actual growth itself due to card effect VFX/buffs obscuring the chest region; if there's some way to delay the growth until after those effects, that'd be great.
Edit 1:
>It seems like increases to base Buxom don't carry over in a run after saving/quitting/resuming a run.

Anyway, keep up the great work.