that souls are pathetic, you need a solid necromancy to make it ever count - and so as necromancer doent have that trait you could just as well not use him at all but the necromancy traited troop alone (which is valk)
atm to cap souls u basically need valkyrie or dragon soul or a lot more time then most of ppl would like to spend per a fight. necromancer doesnt change anything in that outcome