I think once you're touching the rays you can't move anymore, Gash could get away because Barry stood above himSo the barrier wasnt an instant kill why didnt he just push them through and then...leave it. He didnt need to have his book burned he would have been fine if he just moved once everyone else was through.
If so that wasnt super clear to me.I think once you're touching the rays you can't move anymore, Gash could get away because Barry stood above him