here's the blood necro build i'm playing with right now:

blood necro skills

awaken the blood, soul leech, vampiric gaze, mark of subversion, life siphon, dark pact, well of blood, and res signet. i've got 15 attribute points for blood magic (17 when awaken the blood is active) and the rest for soul leeching.

it's working pretty well and even giving me nice win streaks on weak teams. well of blood is so great. just tell your team before the match about it so they know to stand in it. the whole team will then have +7 health regen for 22 seconds. use soul leech to stop monks and mark of subversion on enemy casters. this build could use some more damage dealing. i think i might drop life siphon because once people start dying and i can get a well of blood up then i don't need life siphon anymore.