The perks in question are Necromancy and Dark Souls. Twin Souls affects it as well, hence the reference to the summon limit. Necromage won't do anything for you in this case unless your target was undead to begin with, in which case the effects of Soul Tear become stronger.
The perks in question are Necromancy and Dark Souls. Twin Souls affects it as well, hence the reference to the summon limit. Necromage won't do anything for you in this case unless your target was undead to begin with, in which case the effects of Soul Tear become stronger.