For major, that would be either undead or astral transformations. The first is brutally good because of lifesteal, but it makes your race ugly. The second doesn't have this problem, and status resistance is very good. Oh, there's the draconic transformation too that's probably best actually. No downside to it in fact.
For minor, I always want magical wards, but sometimes both t1 tomes are needed. For melee, supergrowth is addictive. With dark culture, it's vessels of chaos. Then I always have either astral blood, revelers heart or joy siphoner, depending on my strategy. Basically joy siphoner for moral or undead build, revelers heart for non undead melee, and astral blood for astral anything.
I'm not really a meta player though, and I'm still experimenting.