Ok so looking at the Karnival of Pain, it looks fine for use with the new codex, but I might allow the following changes:
-Allow Wracks as well as Grotesques, since the old dex didn't have both types.
- Allow the 3 Haemonculi can be ancient ones as well, but I'd be easier if they were all one or all the other.
-I would also say the drugs you roll for the formation should be the same as the rest of the army since you only now make one roll, rather than one per unit. The roll per turn I'd keep.