O'Seamus is a Leprechaun who delights in playing practical jokes on visitors to Balthus Dire's Citadel. Pranks include firing ripe tomatoes at a visitor as soon as he enters O'Seamus' chamber, and illusions such as giving the visitor the impression he is being mauled to death by an unseen monster. However the "victim" invariably sees the funny side of these jokes when they see the Leprechaun rolling about in hysterics at their expense!