mtg volcanic eruption useful with 0 mana how gatherer

[magicstudent]

I was looking at gatherer at this card:

Volcanic Eruption

sorcery xuuu
Destroy X target Mountains. Volcanic Eruption deals damage to each creature and each player equal to the number of Mountains destroyed this way.

The rulings say about using it with x equals zero:

"10/4/2004 Can be used with X equal to zero. This is useful if no Mountains are on the battlefield."

But I dont get how it is useful when you use it that way

[Void Elemental]

Just because you can play it for 0 doesn't mean it's supposed to be useful set at 0. If you're looking for a use, though, it can be used for Eye of the Storm or for adding to storm count, etc.

[kip]

here is a situation where it can be useful:

you are at 1 life and opponent is at 1 life

opponent has five creatures, four of them tapped and one of them untapped. The untapped one does not have flying. obviously once his turn comes he will win cuz he will attack you with all his creatures and you are at 1 life and only have one creature left and thats not enogh to block all his creatures even if you leave your creature untapped.

you have a Tibor and Lumia but theres no point attacking cuz you will get blocked by the untapped creature without flying and that wont do you any good

also you have three untapped islands

you have only one card in your hand Volcanic Eruption which appears not to do you any good because your opponent happens to be playing his U/B/W/G deck and has no mountains in play

but then you realize you can cast the volcanic eruption with 0 for x and that way you have enough mana to cast it so you tap your three islands and you cast the volcanic eruption and since you cast a blue spell you give your tibor lumia flying and it cannot be blocked by his untapped creature and you attack and you win the game