You need to meet with Scarlet and ask for protection, she'll then spend two days casting a spell on you so that you can with stand being shot by Zenelith's magic. Remember to visit Scarlet both days that she is preparing the spell.
Ohhh ok, I'm gonna restart my whole progress again, because I'm in the last day and forgot to save it
you could look at the autosave, see if there is a good place to restart there, but i might be too late
