Old Alexstrasza kill

Anyone knows whats the synergy to make Alex kill the opponent,when having 14 HP/15 Armor?Cause thats what happened to me just now and im still scratching my head why.Isnt old Alex supposed to reduce someone’s HP -yours or opponents- to 15?
I had a warlock using Alex on me(nothing else played that turn) killing me with Alex,with me having the above stats.Am i missing smt?At the old days when we used to play Alex,it wasnt a life sucker xD

Wasn’t it something to do with azerite snake