MA board of pharmacy put out a letter for
That will give you convenient links to all the potential material on the MPJE-MA.
Focus on 247 CMR, DEA Pharmacist's manual, MA BOP policies/advisories. The policies and advisories seem like a lot to read, but they are 3 pages each at most and really clarify some regulations and in some cases, are repetitive enough that you feel like, "alright alright, I got it." There's no excuse to not reading the 247 CMR, it is the meat and bones of the MPJE-MA and it will directly affect your practice in MA in many ways.
105 CMR is good to know - look at what MA defines as "mid-level practitioners" who can prescribe. What can they prescribe? In what situations can they have certain controlled substances?
MGL c94 is good to read, as dry as it is. It overlaps with the federal law on some concepts, but there are MA-specific requirements in this section you should know such as who to report to when something happens with a controlled substance.
I used RXprep MPJE for the federal law review and found it helpful.
No excuse to not knowing what adulteration and misbranding means. They've got their separate links in that letter, and are specific MPJE-tested points according to the NAPLEX/MPJE bulletin. It's going to come up, like it or not.