Constantly chuckling from both mouths, there seems to be nothing that the Madcap does not find uproariously funny, though its favorite "joke" is to drive other creatures to insanity. Able to read the memories of any sentient being, it torments them with deranged and grotesque illusions of great personal significance, preying upon deeply hidden phobias and buried tragedies. One common tactic of the Madcap is to fabricate a "haunting."
Though large and strong, a Madcap's body is as light and buoyant as an air-filled balloon. This can be a hindrance to the creature when agility is neccessary, and it often pulls itself along with its arms.
I like the idea of them being their own class entirely ... it would be interesting in-game to have some of the old versions of these monsters be alternate sprites that would only occur rarely in the monster creation process