The first two books in a madcap, frothy light series.
At the center of it is Castle Perilous, the castle with 144,000 aspects -- which form portals to other worlds, some stable and some not. In the first book, Gene and Linda stumble in from our world, and the great ursine Snowclaw from another. Meanwhile the castle is besieged by an army and a sorceress in its own world. Various Guests stumble over learning the Castle's ways and discovering whatever magical power it endows them with -- everyone gets one, from fighting ability to walking through walls to materializing things -- during the attacks. Its master Incarnadine is working on various defenses, mostly magical. It involves hamburgers, the problem of finding some portals, a golf course behind one stable portal, computer technology that clearly indicates the date of its first being written, and more.
In the second, Incarnadine goes to Earth to try to stablize the portal, among other things. Bluefaced creatures invade and make themselves unpleasant, but are only the cat's paws. It involves climbing stairs up and down, going through a portal to a jungle, Sheila arriving while she had been taking a shower, Snowclaw returning from his own world, and more.