When did Galactus fight Mephisto?

[MajinShenron]

My question is, when did Galactus fight Mephisto? I heard it was in a graphic novel, but I would like to know which one, thank you.

 

[Johnny Blaze]

It was in the Silver Surfer: Judgement Day GN.

In it the Surfer and then Herald Nova get captured by Mephisto and Galactus comes to Mephisto's realm to get them back.

For a more detail description, follow the link and scroll down a bit: SS: JD