for attributes I go for a balanced Health/Magicka build.  The Necromancer can be very magic heavy on the skills so building this out still gives you above average health pools w/ food buff and a decent magicka pool.  Adding spirit mender to your skill rotation will also increase your magicka regen.  You can use a bit more stamina in this build, however it is much quicker to use heavy attacks with your front bar sword & Shield than swapping to your back bar to try to regain magicka.

​

I built my tank's attribute/gear setups to where majority of the player base can obtain the items.  This is the reason I do not go full health.  You can swap out the health enchantments on armor for the multi-effect enchants, but that requires going into PVP zones which not everyone is comfortable with.  If you do use them, you can swap out health enchants for those and put more attributes into health.