What happens if you fail to bind it?

It specifically attacks the caster, the one that forced it there in the first place, and it kills him or her and leaves, since it didn't want to be there in the first place...

I meant the summoned beast... I just want to know what it would say in the book about it.

And I'd assume if you fail to bind it it kills you. Kills you dead and gorges itself on your blood.

Edit: As always, I'm right.

By leaves, do you mean stays in our world and goes somewhere else, or leaves back to it's world?

It goes back to wherever it came from. If it is a creature from another dimension and it can, it returns to it's own dimension. If it is a creature that walks the earth (Some monsters can only be summoned in very specific circumstances), then it just leaves the group and goes back to whatever it was doing before it was summoned. Basically, mosnters don't like to be pushed around, and they go back to doing their own thing unless forced.

Also... I have a question, that has little relevance on anything:

Let's say Cthulu invades the world... and one of us knows Hastur's song. Now let's say that person manages to survive at first and train about 100 other people in how to cast the spell... now the next time they're able to cast the spell, would it be plausible that they pop Cthulu like a zit being hit by that many Hastur's songs at once?

Hastur's song doesn't overlap. Every time it is cast, the second one overlaps the first and negates it. Only one person can cast it at a time, thus an easy way to defend against it is if one person learns it and a cultists uses it, the person can just use it to counter the cultist.

Awww... too bad. I'd love to see something as big as cthulu explode like that...

Cthulhu is over 100 stories tall, he could easily smash a whole army of people singing Hastur's Song anway...

Anymore Call rleated questions? The description of the beast in question is coming up... Oh, and krylo, you gain +1 Cthulhu Mythos point for reading the diary.

What if you did rapid fore Hastur songs? (Not sure if technology for this is available yet though) You record some one singing the song, then you make many copies and fast forward through one, then when its done start another, and so on.