Gonna be honest, the Addiction boss was way too strong. 1200 hp, massive debuffs thanks to addictions, and an attack that hits way too hard. My advice is to nerf it into the ground, it does NOT need to be anywhere near that strong.
That wasn't my experience with Dungeon 13 (as discussed above)... though it's certainly not guaranteed that players would have the foresight to keep a hard-hitting party member free of drugs. Still, there's plenty of powerful debuffs unlocked by this point, and a solo boss that only does one type of damage isn't THAT scary, especially if you save in advance and retool for debuffing the damage type they deal (and with multiple debuff-all techniques unlocked by now, I came prepared without needing to scum the fight).
Easy solution is to stack some attack debuffs early on and inner focus on Madoka while the other girls put some more debuffs on themselves. Once Madoka's got a stack of 4 and the enemy's got s decent number of debuffs going Madoka can just spam a special attack for 200+ and whittle it down while it can only do 4-6 damage.