There is probably a reference to that in Bored of the Rings.
There it is.
In the book, I recall, the horses (which are mortal horses) are driven to madness by the magic of the river, and the riders lose control of them.
In BotR, they used a magic snowglobe (that contained a carbon arc lamp), and a can of insect repellent to fight off Schlob. Both were gifts from Lavalier.
If “fight off” can be said to include a cutaway that ends a chapter with Frito and Spam one second from being devoured and when we next see them they’re saying “that was close indeed!” 
An epic drama! 
In Letter #397 from “Letters of Harvard Lampoon”, it was revealed that it was intended that the insect repellent be a gift from Cellophane, but this fact was improperly edited out by a drunken undergrad from Rutgers.