X-amining Excalibur #38

"Out on a Limbo - Book Two of The Promethium Exchange"
June 1991

In a Nutshell 
The West Coast Avengers join the fight against Dr. Doom in Limbo. 

Writer: Lobdell
Artist: Badger 
Letterer: Spike
Colorist: Vancata
Editor: Kavanaugh
Editor-in-Chief: DeFalco

Plot
In Limbo, Excalibur is attacked by the demonic simulacrums of various superheroes, while back on Earth, the Avengers West Coast are greeted by Alistair Stuart outside Excalibur's lighthouse. The Lady of the Lake explains that Doom intends to destroy Limbo in order to gain its promethium, at which point England will be sucked into Limbo through five portals scattered throughout the country. She then teleports the Avengers into Limbo. Excalibur and the Avengers split into five teams, intending to destroy the portals then rendezvous at Doom's castle. They manage to close the portals, but are unable to stop Doom, observed by the demon Darkoth, from plunging the Soulsword into the heart of Limbo, transforming all of its native inhabitants into promethium.   

X-amining Excalibur #37

"House Call: Book One of The Promethium Exchange"
May 1991

In a Nutshell 
Dr. Doom tricks Kitty into taking him to Limbo. 

Doing that Story Thing: Scott Lobdell & Mark Badger 
Letters and Hues: Chris Eliopoulis & Glynis Oliver
On Bass: Terry Kavanaugh
On Lead Vocals: Tom DeFalco

Plot
As Meggan is making the rest of the team breakfast, Dr. Doom arrives, seeking Kitty's help in traveling to Limbo to acquire a metal known as promethium, which could provide inexhaustible energy to the world for all time. Excalibur is suspicious, but Doom allows Rachel to read his mind and she discovers no presence of real evil, so Kitty agrees to help. Drawing Illyana's Soulsword, Kitty opens a portal to Limbo and, with the help of Dr. Doom's sorcery, travel there, followed surreptitiously by the rest of the team. In Limbo, the pair is attacked by demons, and Doom grabs the sword from Kitty, fighting them off but revealing that he only intends to provide the promethium to the countries which swear allegiance to him.