Love route didn't have as much degen scenes (which makes sense) but I don't remember the other books really having anything more degen by comparison. They all had public fucking which Book 4 has as well in both routes, but I'm blanking on what else would be considered more degen.
Book 1 slave you can make Katara walk around her village in revealing clothes or completely nude with nothing but cum on her face and tits as a way to encourage her to be more confident in her self (surprisingly it works).
Book 2 love & slave had you making money primarily off enslaving captured soldiers, impregnating them, and then selling their breast milk. You even give them drugs to make the pregnancy last days instead of months. While this was written as a way to "increase the population of the fire nation" after years at war, these women were all giving birth to the bastards of the fire lord (so really it was your personal slave harem/breeding program). You could also choose to have sex with girls that were already pregnant if you wanted, which really just drives home the slave harem part.
While Rei agrees because she thinks she needs your help, you are exchanging sexual favors with her for military advice.
Specifically in the slave route you can make Ty Lee drink fresh piss from a mug in the bar she works in.
In the love route you fuck your sister in front of your girl friend while you all are on vacation.
Book 3 slave had you learning to hypnotize women, making them work in a brothel, as a bar maid who enjoys being berated and doesn't wear panties, as well as two personal fuck toys (Ajala/Jo Dee). One of the girls you hypnotize and turn into your fuck toy ends up pregnant with your child; you later just leave her that way as you have more important things to worry about. You lure in a worried mother and have sex with her (and impregnate her) while her run away daughter watches and later joins in. And while you do get consent, you are technically trading sexual favors for releasing multiple prisoners. Toph is pretty young too.
In the love route, you can
choose to abuse your position of power while you explore the tunnels under the lake and have the three mean girls lick your dick and then leave them locked up so you can cum (heh) back multiple times. There's skybyson masturbation scene if you want it.
All the books have some pretty degenerate stuff from a vanilla point of view, which is exactly why I like it so much.
