I didn't make it remotely hard as dark souls is. People can beat every single boss in this game without getting hit, and I'm sure you could do it too.
E99 isn't difficult: just look at what he is doing and plan a strategy. Do notcharge forward and try to hit him before he shoots. You should have determined it isn't the right way to do it by now.
Keep your distance, jump above the laser 3 times, close the gap and hit E99.