Rich is a summon spell and appears as an undead mage that spits out a blast of black lightning as it flies overhead. This attack is especially effective against Lucavi demons as it can even do 999 damage to Altima. This is because Rich's attack works by dealing half of a monster's maximum health in damage, and bosses such as Altima have well over the 1998 health required to reach to the damage cap.
It costs 40 MP to summon, has a speed of 12, and needs 600 JP to learn. Rich has a 20% chance of randomly being learned in battle by a Summoner who has not yet learned it and is not KO'd by it, or absorbs at least 1 HP worth of damage. Nullifying the damage does not count.
In the original PlayStation version, when summoned, the summoner will sometimes mutter, "Death song, death door, death river awaiting! Rich!". This was removed from the Final Fantasy Tactics: The War of the Lions.