Rain spells function like so: 
 
They hit a total of 4 times (excluding yourself), so if four mobs in radius each mob gets hit once and you get hit 3 times. 
 
If 3 mobs in radius 1 gets hit twice, 2 get hit once, you get hit 3 times 
If 2 mobs in radius 2 get hit twice you get hit 3 times 
If 1 mob in radius 1 gets hit 3, times you get hit 3 times 
 
***Currently*** there is a bug 
Pets are counting as 'mobs' and eating up those hits and fully resisting them.  Were there pets in range when you were using it? 
		
		
		
		
		
		
		 |