Please please please tell me you didn't use any revives at him so far
Yeah, you are probably best to start over. If this is your first time fighting GM it might take you upwards of 2k units of revives to beat him. I would suggest restarting the path and practicing fighting GM until you get him down to 60% health before you start using revives. Not to mention, you don’t have a reverse control immune champion in your team, so you are going to have problems with the third phase.
I feel so bad for you. 1 unit at the start.
After a long grind in arena again All your team is dead and you haven't put a dent? I advise you restart and come back with more units /revives
After a long grind in arena again
GL man! I just did it today and it was super fun. It looks like you have it all under control rn!