Last puzzle of the starter pack?

I finally decided to start doing puzzles, got through the starter pack fine until the last one. I tried dozens of times and I can't get it. I even looked it up on youtube and I do EXACTLY what they do and I still die. I pick up the IMAWAL glyph, petrify the goo, attack the gorgon once, get the message about death protection and it says carry on fighting, I attack again and use up my death protection. At this point in the video, that second attack kills the gorgon, but for me it still has a little heath left and when I attack again I die.
What am I doing wrong?
What am I doing wrong?