Why?

Ok, today i was making some ubers with my _SUMMON_ Necro
this is how it went:
izu and duri was izi
then i tried to kill lilith..
first, my merc died like 8 times (lvl 19 conc there)
then i started tank with glay golem (13k life + bo)
then it went VERY WELL!!
at the end, lilith had like 3% life left..
(i had like 5 of my 16 skeles left due fucking poison)
poison damage got up with me too
i had 1 life left (after poison)
THEN ALL THE SUDDENLY
"Korroosio was slain by evil force"
Slain by evil force
Slain by evilSlain bySlain:cry: :cry: :cry: :cry: :cry: :cry: :cry: :cry:

/edit:
lilith killed my merc with 2 hits omg