Battle a monster that is worth a large amount of experience points, such as a red or blue dragon. After killing the creatures, do not search the body for items. Then, cast Paralyze on the dead monster, to bring it back to life. It may now be killed with one successful hit to collect its experience points. Repeat this to rapidly accrue experience.
Potions
Expert potions
Use the following combinations to create Expert level potions:
Green + Blue = Recharge Item (Green/Blue)
Green + Yellow = Harden Item (Green/Yellow)
Green + Red = Bless (Green/Red)
Green + Orange = Cure Insanity (Green/Orange)
Green + Purple = Remove Curse (Green/Purple)
Orange + Red = Haste (Orange/Red)
Orange + Yellow = Stone Skin (Orange/Yellow)
Orange + Blue = Preservation (Orange/Blue)
Orange + Purple = Remove Fear (Orange/Purple)
Purple + Red = Heroism (Purple/Red)
Purple + Yellow = Water Breathing (Purple/Yellow)
Purple + Blue = Shield (Purple/Blue)
Master potions
Use the following combinations to create Master level potions: