When trying to kill the Enner via melee (a mistake I make far too often), don't stand next to him horizontally or vertically; you'll take less damage if you stand next to him diagonally.
Here's the formula for the strength of his scream:
int ScreamStrength = int(70 / (hypot(GetPos().X - x, GetPos().Y - y) + 1));
Since it calculates your distance from him based on hypotenuse, standing diagonally will count as being 1 square away (even though you can still attack him diagonally), causing the strength of his scream to be halved.
Ex.
E = Enner
P = Player
###
#EP
###
Here there is no hypotenuse, so the scream strength is
(70/(0+1)) = 70.
E = Enner
P = Player
##P
#E#
###
Here the hypotenuse is 1, so the scream strength is
(70/(1+1)) = 35.
I tested it out in wizard mode, and with no armor you take around 24 damage when at an angle and 32 damage when directly next to him (of course this doesn't matter at low End since vitals like your head and groin can be killed instantly).