How powerful was Brahmastra? [duplicate]

Question

There's a weapon discussed in Mahabharata called Brahmastra. Maybe Bhishma and Drona had this weapon.

How powerful was it? If any person used it, would it destroy whole world? Was there any technique/way to respond to it and make it fail once it is released by someone? Or once released, it will destroy the world?

EDIT: Now since it seems a duplicate, let me add more details to clarify why I need answer for it.

In a few answers earlier on different questions, I read that "Arjuna or someone fired Brahmastra on Karna. The story after being fired is not described. Nobody knows what happened." Then the author concluded that since Karna was still alive, it must have been destroyed with ordinary arrows.

Unfortunately, I can't find those questions and answers, but I'm sure I read it.

EDIT 2: If you still not ready to remove it as duplicate, let me add further details. In Star Plus Mahabharata, it is shown that Brahmastra fired by Ashwathama attacks only the womb of Uttara. No point of destroying whole world. Secondly, it is also shown that Brahmastra fired by Arjuna to counter attack Ashwathama's Brahmastra, withdrawn back by Arjuna after Krishna told him to do so.

Answer 1

The divine weapon with no match, which was used by Aswatthama is not bramAstra, but brahmashira, is capable of consuming the whole world.

According to the Mahabharata, it acts at the wish of the user.

Ashvatthama, who was no match to Arjuna, uttered in wrath, while discharging brahmashira, these terrible words: ‘For the destruction of the Pandavas.

At the behest of Krishna, Arjuna also discharged brahmashira to contain the one discharged by Ashvatthama, thinking of the welfare of all the worlds and uttering the words, ‘Let Ashvatthama's weapon be neutralised by this weapon!'.

Fearing collision of 2 brahmashira weapons, Sage Narada and Sage Vyasa stop them, by standing between them. Later at the advise of Sage Vyasa, Arjuna withdraws the brahmashira discharged by him.

As Ashvatthama is incapable of withdrawing his weapon, changes the direction towards wombs of the Pandava women. The foetus in the Uttara's womb dies due to its attack.