To summon the Outsider, the wizard must make a successful Spellcraft check at DC 20.
The Ring of Set, though incredibly powerful, is not without dangers. The mortal mind suffers incredible stress from contact with these entities and powers, often leading to madness. The formulas learned from the creatures summoned, once held in memory, strain to escape, almost like living things; once uttered, they are immediately forgotten. Also, these alien Entities from Outside Time and Space may take undue notice of the wizard who enters their realm.
Any spell is available to the wearer of the Ring of Set, be it Divine or Arcane, Bard, Paladin, Ranger, Druid, or Domain. If the spell is usable by multiple classes and has several different spell levels depending on class, use the lowest spell level when determining difficulty. The wizard must make a spellcraft check to be able to grasp the terrible things he hears from the creature summoned. The DC for this check is 25+spell level. If the wizard has a catastrophic failure (ie. He rolls a natural 1 on the check), then the summoned creature is free to attack the wizard.
If the wizard fails the intelligence check, but a catastrophe does not occur, then he merely loses his mind. He must now make a Will save against the same DC the spellcraft check was made at. If this succeeds, then he merely loses all memorized spells. If this fails, he is struck insane. (see the insanity chart on the Alienism page to determine type of insanity.)
If the intelligence check is successful, the wizard has a new spell to cast. If the wizard has some tome or scroll that identifies the spell he is trying to learn (such as the Book of Skelos or the Codex of Infinite Planes), and reads of this before entering the trance that sends his consciousness outward, he gains a +1 on his DC checks.
Howard also used Thoth-Amon's copper ring and its attendant baboon demon in a story with a modern setting, "The Haunter of the Ring."
