First solo success against Fatalis

If you want to beat Fatalis then i suggest getting divine blessing secret lvl 5, crit eye and exploit max, 2 crit boost, part breaker lvl 2 and MOST important for light weapons shaver jewel (if you are short on spare decos craft the charm) and if u have 2 fatty armour already do most (or all if u can) of the above and get max might lvl 5 for that beautiful +40% affinity. As for the strat i used, go in w/ ghillie and load the cannons and aim the eastmost cannon a little to the right and the westmost to the far right as fatty WILL charge at you (currently on the far right) after you shoot the eastmost cannon. Following these steps (with heavy artillery lvl 2) will take over 5% of his hp right off the bat and topple him for you to tenderize his head and get good damage in. The heavy artillery will also affect the ROAMING ballista massively later on. After the first flame flood just do whatever to kill it, hopefully breaking the chest then the head soon after the 2nd flood + near the end.