Enchanter/Shaman/Mage/Necro with 4x bio orbs would be my pick for Harla Dar if she can be blind kited. 
 
Enchanter focuses on Tash, Slow, Clarity, and Group Resist MR. 
 
Shaman focues on Malo, Healing, and DoTs. This would be a very slow and long fight, so you want a Shaman to be able to maintain their mana, and they get a free DoT clickie via Epic. Could Torpor the pets too as long as your DPS is slowly reducing HP. 
 
Necromancer does DoTs and twitches. Can use their pet if the Mage needs a break. Can res if something goes bad. 
 
Mage just saves all mana for pet chaining to keep Harla Dar in place. 
 
All group members would need to be bio orbing as often as possible. The group would need to be well coordinated so when one caster is doing something, like a Necromancer Doting, at least one or two other members are bio orbing. 
 
Once Harla Dar is down to Gating HP, Mage stops using pet and switches to doing nothing but spamming bio orb. Necro also stops using their pet, and focuses more on DoTs. 
		
		
		
		
		
			
		
		
		
		
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