Ok imma give you all the information you need being that i leveled up Wrilt and Zalakus on Mars Fist both from 0 to 60 plus 900 CMS
Necromancers pact wich gives heals, plus there blood/mana paths are real useful, while the mage paths are useless when comparing to a Necromancers normals procs. But Heres some information at 60 -
If your geo as a Mage then your pet can tank way better than a necro pet, so if u want ur pet to tank be a Mage Geo, If you want to solo GREATLY like i did, go Hydro bc GN rocks outta all the pets for soloing IMO, dont really need to meantion Pyro and Aero if u want damage bc BSD owns em all.
If u want solo or tanking be a mage Geo/Hydro, If u want to do MASSIVE damage and a heal when its needed, be a Nec.