The Ogre is very agile and hits hard but can be beaten by inflicting it with Degenerate and buffing your equipment with Prostasia. When attacked, use Reflect Damage as your Defensive ability. Do not use Chain abilities as they will miss and raise your Risk for no reason. Piercing weapons work well against the Head and two Arms targets. You could try attacking one of its legs to cripple it and keep it in a corner. If your risk gets high, use a Vera item.