Mages are limited as to amount of mana they may spend on a single spell. By default, this “Spell Mana Limit” is 6. If a mage casts a spell which costs greater mana than his Spell Mana Limit, he immediately rolls 4dF, adds the difference between the mana cost of the spell and his Spell Mana Limit, and applies the result on the calamity table.
Spending Fudge Points allows the mage to shift the calamity result up one level per Fudge Point spent.