The [Lunacy Deck] can be turned in at Darkmoon Faire to get the Darkmoon Card: Madness. In addition to 51 stamina, this trinket has an effect that whenever you land a killing blow on a target, you randomly get one of the following buffs (in which your class is listed):
Each buff lasts for 30 seconds.
Delusional
Attack power increased by 70.
Rogue, Hunter, Paladin, Warrior, Druid, Shaman
Dementia
Down the rabbit hole... Dementia: Damage and healing from spells and effects is increased. (5% for 5 secs) Dementia: Damage and healing from spells and effects is reduced. (5% for 5 secs)
Druid, Shaman, Priest, Warlock, Mage, Paladin
Kleptomania
Agility increased by 35.
Warrior, Rogue, Paladin, Hunter, Druid
Manic
Spell, melee, and ranged haste rating increased by 35.
Spell, melee, and ranged critical strike rating increased by 35.
All Classes
Sociopath
Strength increased by 35.
Paladin, Rogue, Druid, Warrior
Triva
When one of the powers procs, there is a chance your character will say "This is Madness!" in reference to the movie 300.
Dementia and mania effects are most likely a reference to The elder scrolls: The shivering isles.