Everything needed for the Necromancer class is already in game.
Once the expansion is over, if you take all of the covenant spells and bring them together, it is a really unique set of spells.
Necromancer is a highly requested class. Most people ask how it would be different from Warlock. Looking at the covenant spells in-game, it is clear that there are many abilities that can make a unique experience.
Also, make it MAIL.