This weekend was the end of the first part of the module A3; the boys are about to enter the city of Sudderham. But before they left the maze they took a long rest.
And then the dream sequence kicked in.
The boys were transported back to the Dawn War where He Who Was was killed by The Destroyer (who will become Demogorgon) and Dis, the god that dies and then becomes the demon Orcus.
The old Dungeons & Dragons toy troll and ogre are Demogorgon and Orcus prior to the battle respectively.
I had them fighting a new creature, well, new "then"; demons.
I ran the game using 30+ level "gods" using the B/X and Companion rules (with some AD&D 1 to smooth out some edges).
It was a lot of fun.
Now to tie it into the current adventure.