Class Requirement. Magic-user or Illusionist only.

Only magic-users can benefit from this type of ring. Other classes, even those with spell ability, can neither use nor understand the working of a ring of wizardry. 

The ring doubles spell ability (i.e. the number of spells a magic-user may prepare each day) in one or more spell levels.

To determine the properties of a given ring use the table below:

Note: The symbol † appearing on the Rings table (III.C.) and in the following descriptions, denotes rings of the most powerful magical abilities, which will often possess a limited number of magical charges at the option of the DM.