Prerequisite: Intelligence 13+
You can cast a spell of 1st through 5th level by expending any combination of lower level spell slots if the combined level is equal to or greater than the level of the spell you wish to cast. For example, casting the level 3 spell fireball by expending one level 2 spell slot and 1 level 1 spell slot. The spell is always cast at its lowest possible level, even if the combined total of the spell slots expended is higher.