It is not that horrible, but inferior to the other. 
 
Well, most mage type units are not that good, both in dmg or survival, they're just there for support. I usually left my rune mage after i got to verona, and using it again in the last island loop (i use unicornxp loop sequence) only for taking on bosses (especially k'tahu).
		 
		
		
		
		
		
		
		
		
	
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