You wont get the magic regeneration in sunlight outside vampire lord form with ring of the Erudite. If you remove all mana regen items and perks and equip the ring, you will not regenerate mana.
Yes you will. Ring of Erudite works outside vampire lord form. Any addition of regeneration, no matter what the size, overrides stunted regeneration. That is why the lady stone works for health/stamina.
As a vampire (non transformed), spent magic bar, in the daylight, wearing nothing...equip the ring and watch, the magic bar refills very very slowly. Not efficiently but it still regenerates.
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