It is recommended to have around 10k-20k stats minimum for DLC3, this is the part of the game where you need to plan your strategy, even mobs will kill you easily here if you dont pay attention and item is almost must have to deal enough damage, some tips is to stack action per turn with black/white rabbit ring, andor sword, Mabel's Pnties or Duchess Pledge and buff yourself with pine item then burst the opponent's, Requiem is a must have and just pay attention to enemy gimmicks
The game will punish you for rushing headfirst without strategy (Fu*king horse), most if not every enemy in DLC3 deal percentage damage and has some gimmick (Cant use item, Convert Heal to damage, cant use skill, etc) so base stats didn't actually matter much except for dealing damage and its recommended to gather every gear up to dlc 3 to counter those gimmicks
Farming souls can be done in Ashen Reignited boss rush, it give you a hefty amount and exchange those for Souls of Outer God from Mabel inside Chaos Dungeon