Blood Support Build ;)

1. Blood Ritual
Description: Sacrifice 17% max health. For 8-13 seconds, target other ally gains energy regeneration of 3. Blood Ritual cannot be used on the caster
Energy Cost: 10
Activation Time: 2 Seconds.
Recharge Time: 2 Seconds.
Linked Attribute: Blood Magic. Increases duration.
Skill Type: Enchantment Spell.

2. Order of Pain
Description: Sacrifice 17% health. For 5 seconds, whenever a party member hits a foe with physical damage, that party member does an additional 3-13 damage.
Energy Cost: 10
Activation Time: 2 Seconds.
Recharge Time: None.
Linked Attribute: Blood Magic. Increases additional damage dealt.
Skill Type: Enchantment Spell

3. Well of Blood
Description: Exploit nearest corpse to create a well of blood at its location. For 8-18 seconds, allies in that area receive health regeneration of 1-5.
Energy Cost: 15
Activation Time: 2 Seconds.
Recharge Time: 2 Seconds.
Linked Attribute: Blood Magic. Increases duration and health regeneration.
Skill Type: Spell.

4. Awaken the Blood
Description: For 20-39 seconds, you gain +2 Blood Magic and +2 Curses, but whenever you sacrifice health, you sacrifice 50% more than the normal amount.
Energy Cost: 10
Activation Time: 1 Second.
Recharge Time: 45 Seconds.
Linked Attribute: Blood Magic. Increases duration.
Skill Type: Enchantment Spell.

5. Offering of Blood
Description: Sacrifice 10% maximum health. You gain 8-18 energy. This is an elite skill.
Energy Cost: 5
Activation Time: 1/4th of a Second.
Recharge Time: 15 Seconds.
Linked Attribute: Blood Magic. Increases energy recovered.
Skill Type: Spell.

6. Demonic Flesh
Description: Sacrifice 20% max health. For 30-54 seconds, your maximum health is increased by 80-176.
Energy Cost: 5
Activation Time: 1 Second.
Recharge Time: 60 Seconds.
Linked Attribute: Blood Magic. Increases health sacrificed, duration, and additional maximum health.
Skill Type: Enchantment Spell.

7. Strip Enchantment
Description: Remove one enchantment from target foe. If an enchantment is removed, you gain 30-102 health.
Energy Cost: 10
Activation Time: 1 Second.
Recharge Time: 20 Seconds.
Linked Attribute: Blood Magic. Increases health recovered.
Skill Type: Spell.

8. Resurrect PvE/Vengeance PvP

This will be a healthdraining support build but will sustain a high energy pool, I suspect it might work. Awaken the blood might be a bad call as nearly all skills require you to sacrifice health
Also this is mainly for PvP and please post suggestions that would make this even better.

Necromancer/Monk

P.S Attribute points:
16 (12+1+3) bloodmagic
13 (12+1) soulreaping

You have the right ideas for blood support but take out awaken the blood because with 16 in blood magic it wont give significant boost to blood skills.
While I happen to love Offering of blood, but with 13 into soul reaping it isn't going to come in handy enoughf to take your elite spot. Best bet would be having 3 base into SR with a +1 rune allowing you to put another 10-12 base points into say curses if you want to use offering of blood. Useing curses may also unlock even more supportive things you can do. These are all just suggestions.

Awaken the Blood, which increases sacrafices, in addition to Demonic Flesh is going to make the sacrafices sting quite a bit.

613 health without any health runes, and if you do have any, up ~650. Assuming you have Awaken the Blood up-

97 health for a 10% (=15%) sacrafice
162 health for a 17% (=25%) sacrafice
195 health for a 20% (=30%) sacrafice

As opposed to-
405 health
41 health for a 10% sacrafice
69 health for a 17% sacrafice
81 health for a 20% sacrafice

You sacrafice ~2.3x more by using those 2 skills.

Since Demonic Flesh only gives more health, which is only good until it's gone, I'd drop it and trust the team's monk to heal, which lowers the damage you take from sacrafices and opens another skill slot.
Awaken the Blood's bonuses are negligable at 16 blood, and cause extra damage from sacraficing. 2 more damage out of OoP, 1 more second for Blood Ritual, 1 more second and an additional pip of regen for Well of Blood, 1-2 more energy from offering of blood. What that's worth depends on you, though. Not as if there're many more skills to choose from blood anyway, so those bonuses may be worth the skill slot.

I sometimes use this kind of support nec in arenas.

Vampiric Gaze
Enfeeble
Faintheartedness
Malaise
Well of Blood
Blood is Power {E}
Strip Enchantment
Res Sig

Attribs:

Blood 16 (12+1+3)
SR 9 (8+1)
Curses 12 (10+2)

yes i was thinking about sacrifices and mana thanks a million guys

Definitely take out awaken the blood, it will get you killed a lot faster when you're using sacrifice spells. Also, depending on where you play I'd probably ditch well of blood as well. In 4v4 arenas you may get some use out of it, but you'll need a corpse to work with first and by that time one team will have the upper hand, and I don't think a well of blood is going to make up for it. In tombs, it's almost guaranteed that a death necro will beat you to any corpse with putrid explosion...

Blood Ritual is useless for the most part. Even at 16 blood you are trading 10 of your energy now to give someone else 15 energy over 15 seconds, ok, a 5 energy gain, fine, but at the cost of 17% of your health and a 2 second casting time. If it stays on the player for the full 15 seconds - if it is a heavily targeted player it could well be stripped in a rend or the like in which case you've hurt yourself and spent 2 seconds and 10 energy... for possibly less than 10 energy being given to your target.

Never liked that spell. At least you have the level of Blood magic that makes it marginally useful, at 10 blood magic it's simplly an acknowlegment of sucking, in that if it helps the party it is only because you are useless enough that moving your energy elsewhere at a cost of 17% of your life is a good thing. Yay Claude [Cultist Henchman]! You give away your energy, you useless putz!