Oykamon was a fat toad who ruled the Toadlands during the time when Mariel Gullwhacker was venturing towards Redwall Abbey. Oykamon and his toads attempted to ambush Mariel/Storm as she was feigning sleep, claiming falsely that she had trespassed on his land and stolen water from his well. Fortunately Colonel Clary, Brigadier Thyme and Honorable Rosemary came to her rescue and chased the toads away. Furious, Oykamon vowed to come back with a full army of toads with tridents and attack the hares, which he did. Hon Rosie defeated him in front of his band by knocking him over with a slingstone.
Oykamon was wise for a toad; he gave out a warning to Mariel the first time, telling her he would return with a full army when she trespassed on their land once more. Most toad leaders are ruthless and savage, and ordinarily would not bother giving warnings to trespassers.