You will return as a party of Lightning, Snow and Sazh. Re-equip everyone as desired and then start bashing Cie’th skulls. Ghasts and Ghouls will litter the path before you as well as a flying Cie’th, a Wight. These can be staggered easily and are quite weak so don’t change your tactics too much. A final, larger group of enemies awaits you at the top but stay aggressive and you won’t have any trouble.
Collect the 5x Potions from the Treasure Sphere before you use the Save Point because you might need them in the next battle. Make sure you have the right accessories equipped and throw a Fortisol on yourself right before you enter the throne room just to give you a further advantage.