Depends on your class. For a Kensai, Potions of Defense are very nice. Potions of Master Thievery can essentially give Thieves unlimited money (though unrealistic and a bit cheesy).
However, I think the Potion of Magic Protection is the best. Paladins and Monks get 100% MR from it. Anyone else can get 100% MR by using 2 of them. |