MAD or multiple ability/attribute dependence in role playing gaming describes a character build that requires multiple attribute or ability scores to be high in order to be viable. Since games typically have limits on increasing multiple scores at once, MAD builds are at a disadvantage against builds that get larger benefits from increasing just one or two scores.
In 4th edition Dungeons & Dragons, star pact warlocks were frequently cited as an example of MAD prior to the warlock update. Prior to the warlock update, star pact warlocks used Constitution for some spells, such as their automatic at-will dire radiance, and Charisma for other spells, such as all doomsayer paragon path spells. This meant star pact warlocks had to restrict themselves to only Constitution- or only Charisma-based spells, or neglect Intelligence-based rider effects.