All 861 two-mastery pairs from the 42 classes in your install, with the mod's own title for each pair. Pairs are rated by shared damage types, weapon style, what each class adds, and the Zenith cross-class bonus skills.
Tiers are relative: S is the top 5% of pairs, A the next 15%, B the next 30%, C the next 30%, and D the bottom 20%.
Pair titles and the Zenith bonus skills come straight from Grimarillion's text files. Each class's damage types and weapon styles were read from its skill names and descriptions. For the vanilla Grim Dawn classes they also draw on general game knowledge, so treat them as a good guide rather than exact values. Attack-replacer warnings are only shown for skills the mod itself labels [Attack Replacer].
Classes that touch many elements, such as Inquisitor, Arcanist and Wizard, can rate high with many partners. Check that the two classes actually boost the same skill you plan to use.