Races who have natural regen, Iksar/Troll, their health goes up while not getting hit. 
Races who don't have that regen, their health does not go up. 
(excluding spells/items/pots) 
 
Spending time spot healing (not cleric healing) I notice their HP go up 1% occasionally. 
Not having natural regen isn't detrimental but it helps. Especially if there is any downtime between pulls and they're not at max hp. 
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You'll most commonly find people arguing over regen vs frontal stun immune. And those debates go in length depending on the class in question. For warrior I think ogre is king but I've seen iksar do just as well. 
		
		
		
		
		
			
		
		
		
		
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