Thanks all, I just did the Justiciar Thommis level and it worked pretty well.
I went with pretty much the setup Iuris said.
Me: W/D
Eremites Attack - Mystic Sweep - Banishing Strike - Whirlwind Attack - Power Attack - Warriors Endurance - Aura of Holy Might - Save Yourselves.
(I took Banishing Strike since there are a lot of summoned creatures there)
Hero 1: N/Mo
Jagged Bones - Animate Bone Minions - Death Nova - Masochism - Extinguish - Protective Spirit - Aegis - Signet of Lost Souls.
( I made a change over the default build and added "Extinguish" since it was the only spell I could find that would remove conditions from the whole party at the same time. I found that it was sorely needed since mhenlo doesn't have a condition removing skill and although the two other heroes can remove conditions it takes too long to do it on all.)
Hero 2: N/Rt
Xinraes Weapon - Weapon of Warding - Mend Body and Soul - Spirit Light - Protective was Kaolai - Life - Signet of Lost Souls - Flesh of My Flesh.
(think that's the default N/Rt healing spec)
Hero 3: Rt/-
Signet of Spirits - Pain - Disenchantment - Spirit Siphon - Ancestor's Rage - Splinter Weapon - Spirit's Gift - Boon of Creation.
(should probably exchange Spirit Siphon for another spirit, I think he has enough energy regen from Boon of Creation already).
Henchies: Mhenlo, Lo Sha, Herta, Cynn.
Again thanks for the help and feel free to give me more good advice or pointers if you have any.