hi
i play on DN a SPS/EE and i eat necro/PP usually (with roughly same stuff)
necro/pp has silence and anchor; but sps/ee has cancel and trance. and you can spam trance a lot. when necro is tranced, this is the end : erase pet, mana burn a lot, nuke^^
necro in C6 is weak due to erase pet and resist unholy buffs. on time a necro/pp silenced me and nuked me (silence is 15 seconds), only 400 damages by skill . at the end of silence, i had again HP and recup my full HP in 2 heals and then trance ...
yeah necro/bishop is good, with PP bot
sps/ee is good for heals, pow, wild magic, but also : erase, invocation, mana burn, arua flare (awesome^^), curse fear, root (yeah root lands a lot with a full buffed sps/ee), ...