In most games, reflect is worthless. Not so in stolen realms (Tested up to third difficulty). This build is more effective the more enemies it has attacking it, and only struggles against enemies which does %max hp on hit.
So, it is much more effective if the "tank" runs in and takes aggro from as many enemies as possible at the start, while the rest of the team runs away to ensure the "tank" gets as much aggro as possible.

This build needs two stats, and two stats only. Strength and Vitality. You can keep them around the same or put 3 in strength and 2 vitality every time or 3 vitality and 2 strength every time (my preference).
You don't want intelligence, that is for smart people. Smart people don't want to be hit, and you do.
You don't want reflex, again, that is for people that don't want to be hit. You want to be hit as much as possible.
ITEMS
THORNS, THORNS, and more THORNS.
You want every item to have reflect on it. Physical reflect is what I usually go for (it is the easiest, but it is hilarious to watch an enemy hit you three or four turns in one turn and apply 4 poison to them each each hit from the poison shield)

Shadow Tree-16 skill points core
First three points:
Start off with Ghost Armor to help keep you alive in the early levels, Call of the Grave to help deal damage the entire game, and Thirst to leech off all damage you deal.
From here you want:
Thirst II For more healing
Vengeful Shadows to heal back 20% of all damage dealt to you and heal back for 25% of that amount
Reaper's Toll to heal you for 10% of your max hp for every enemy that dies.
Consumption to reduce enemies max hp and raise your max hp.
Soul Fracture to lower bosses HP and mana by 20%.
Dark Ritual to keep you alive in a pinch.
Leech Might to gain might on groups when you use consumption (or off autos)
Vampiric Aura if you get any type of mana regen. The Enchanted Pumpkin is perhaps the best Fortune for this build, as it gives you hp and mana regen per turn.
Reaper's Scythe to deal a lot of damage to pesky high hp enemies. Use this on enemies below 50% hp to get the bonus 20% damage.
Soul Exchange in nich situations where there is an enemy with High HP when you are low HP.
Immortal Night[b/] So you finally die, well who cares. you can revive 3 times with this. (You WILL lose 25% max hp and mana each time, but if you can cast dark ritual again each time.....)
And that is the core build.
Optional Shadow tree: 7 skill points
Child of the Abyss will stop HP regen, but give you 50% damage reduction and only allow you to heal from lifesteal (you have 45% with your passive and vamp aura+ you may have some from an item.)
Leech Dexterity to increase your damage after using consumption or autos.
Exocism is viable to remove a pesky buff.

There are several trees you can use with this build for your remaining skill points, but I will leave that up to you.

CONS
Dot enemies hurt you a lot (which is why I generally don't take Child of the Abyss).
Enemies that do 20% max HP on hit can kill you at 5 stacks. (Why you take Dark ritual and why its good to have damage behind you.)
That is pretty much it.

HAVE FUN!