I think Harla is probably the hardest of the 5.  She can be slowed and blinded, but is very resistant.  I've seen a shaman burn their whole mana bar trying and falling before with tash and malo, but I've also seen it land. 
 
Some sort of preslow might be possible, but I wouldn't count on landing effects during the fight.  I think you have to fight on spawn to stop gate as well, since I'm pretty sure she regens more than gate mana per tick.  
 
If you're going to do vaniki, you would want to sell loot rights ahead of time I think.  A lot of high value camps don't necessarily hold value for 4 specific casters after all. 
		
		
		
		
		
			
		
		
		
		
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