Which one is better? Necromancy specialty increases your skill efficiency every level, that means more skeletons, while Skeleton Specialty makes your skeleton better starting with level 1, but it's capped at 300% damage.
Best is probably to have speciality on secondary, but it doesn't help much.
Best is Galthran, Necromancy is capped anyway and Galthran has an easier time reaching the cap faster due to his larger starting army.
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Living time backwards