Here is a good look for a slave:
female:
male:
FoW Armor:
Female:

Male:


Attribute Points:
Energy Magic: All allies adjactant to your location gain +1% energy regen. per point. (No sup. or major Rune)
Holy Magic: Improves Holy Magic Skills. Allows you to cast skills on allies to give them additional energy regeneration.
*Controler Magic: Improves Controler Magic Skills. Helps remove hexes/enchants/conditions/etc...
Hand Magic: Improves Hand Magic Skills. Just helps out/supports minions, inturupts, and skill recharge.
Some Skill Ideas **ALL ATTRIBUTES AT 16 POINTS *=elite skill
Holy Magic Skills:
Holy Ritual: Energy 10: Gives touched allie a +6 energy Regeneration for 15 seconds.
Givings of a Life: Energy 5: Sac. 10% energy. Give target allie 10 energy.
Power of Disproval: Energy 10: After 21 seconds target allie gains 15 energy.
*Holy Is Power: Energy 5: Gives target allie +7 energy Regen.
and so on...
Control Magic:
Smash Hexes: Energy 5: Remove a hex from target allie.
Corrupt Hexes: Energy 10: Remove up to 3 hexes from target allie.
Vanish Enchantments: Energy 10: Remove up to two enchantments from target foe.
Displease Enchantments: Energy 25: Remove all enchantments from target allie and all foes adjanctant to target allie take 50 damage per enchantment.
Remove Conditions: Energy 10: Remove up to three conditions from target allie and allie is healed for 20 health per condition.
Conditioning: Energy 15: Remove up to three conditions from target allie and place them on the caster of these conditions.
*Diminish The Casted: Remove all Enchants/Conditions/Hexes on battleground and all allies gain 20 energy.
Hand Magic:
Heal The Dead: Energy 10: Heal all allied adjactant minions for 100 health.
Suffering of Chaos: Energy 10: Recieve -5 Health Degen but all adjactant minions recieve a +5 energy Regen.
Inturupting: Energy 5: Inturupt target foe's current action.
Removing Skills: Energy 15: For 5 seconds target foe cannot cast.
Horror Of The Blood: Energy 10: Recharge the next skill casted by target foe 50% faster.
Relms Of Recharge: Energy 15: Recharge all of target allie's skills.
*Recharge of Might: Energy 25: Recharge all adjactant allies skills and your skills are disabled for there recharge time.
I think the average Slave should be granted:
350 health
50 energy
Weapons: Wand-like

Damage: 15-22 (Req Holy, Control, Or Hand Magic)
1 handed (ALL 1-HANDED)
Possible Perfect Mods:
Normal game Mods:
Offhand:
Energy +12
Normal Game Mods