A lot has been written regarding how difficult this quest is, surviving against those six statues that come to life shooting fire bolts at Geralt.
Someone said that you need to run up the stairs as they do not follow and from the landing you can use your crossbow and bombs on them safe from their fire bolts.
I familiarized where the stairs were in relation to where I had to kneel, ready to run as soon as they came to life.
Easier said than done. They immediately surrounded me and automatically being in combat mode I could not run
but was forced to fight. After numerous re-loads I managed to get up the stairs. From the landing you can save, meditate
and bomb them.