The magazine assumes you have the Inquisitor rulebook (often called the "Living Rulebook" because of fan updates). A free, fan-maintained version called exists in PDF form and is legally distributed. Use it alongside the magazine PDFs.
If you have never read the magazine before, prioritize these issues in your hunt: inquisitor magazine pdf
It published some of the earliest rules for Titans and super-heavy vehicles in 40K, which were essential for those buying the large kits from Armorcast . The magazine assumes you have the Inquisitor rulebook
For many years, fans of the =][= symbol sought out physical copies of these magazines on eBay and in discount bins at conventions. However, the physical degradation of paper and the scarcity of back issues made access difficult. Enter the digital revolution. inquisitor magazine pdf