I'd say summon an NPC or another player if you can. If you HAVE to solo her then I'd say the best method is: Attack twice then roll away from the Boss. Around attack 3-4 she will attack you or do her backstep/attack so limiting your attacks to 2 or using magic are really useful methods. As for the limited light. Just block and use your lock on button until it locks on then wait for a chance to attack.