That's awesome! I'm glad those animal synergies are paying off - until recently rat king only absorbed rats so it was kinda narrow, i think it was a good change to broaden the effect. Agreed its hard to make work with cerberus. Fire decks are tricky, they used to revolve around cinders but i changed that so now im not sure. My favorite has got to be deer + tombstone - so silly to set up little point machines.
Deer and tombstone is a really fun combo to get. And the rat king change does sound like it made it a lot more viable.
I'd love to see even more done with the game if that ends up being a direction you wanna take it and enjoy working on it. I haven't ever played Dorfromantik, but I love Slay the Spire and it also has a similar vibe to Backpack Hero. Maybe if all three had a very weird baby lol. Either way, I've been having a ton of fun and definitely gives that Spire dopamine I can see myself coming back to get again and again.