11/17/2017 For example, if X is 5 and you choose three target creatures, Fireball has a total cost of (even though its mana cost is just and its converted mana cost is 6). If those creatures are all still legal targets as Fireball resolves, it deals 1 damage to each of them.

11/17/2017 You may cast Fireball with zero targets, regardless of the value chosen for X. If you do so, it will not be a targeted spell, and no damage will actually be dealt when it resolves.

11/17/2017 Fireball¡¯s damage is divided as Fireball resolves, not as it¡¯s cast, because there are no choices involved. The division involves only targets that are still legal as Fireball resolves.

11/17/2017 You can target more than X creatures. However, if the number of legal targets at the time Fireball resolves is greater than X, none of them will be dealt any damage.