Raavan had several boons to be invincible by many, and in this process he won all Devtaa many kings, and many Raakshas and brought many women from there.

Raavan Becomes Immortal - Once he did severe Tap for Brahmaa Jee. He offered him his 9 heads as Aahuti. When he was about to offer his 10th head, Brahmaa Jee appeared and bestowed him with the boon of his liking. He wanted to be immortal, but Brahmaa Jee said - "I am also not immortal, how can I make you immortal?". Then he thought of absolute supremacy. He was not afraid of human beings and monkeys but of Devtaa, Raakshas, Gandharv and Yaksh; so he asked him - "I should not be killed by any Devtaa, or Yaksh, or Raakshas, or Gandharv, or heavenly spirits, or serpents or wild beasts." "So be it." and Brahmaa Jee got disappeared. Thus he considered himself now invincible.

After this he got the boon of long life from Shiv Jee also (read "How He Got the Name Raavan?")

Raavan Loses Shiv Jee

Once he did severe Tap for Shiv Jee. Pleased by his Tap, Shiv Jee appeared and asked him to ask for any boon he liked. He asked him to live in his city. Shiv Jee did not like to live in Lankaa, but he could not go back from his words, so he gave a thought and said to him - "I can live in your city but you will have to carry me yourself, and since I cannot go in my present form, you take my Ling there. There is one condition that when you will carry my Ling, you will not keep it on ground. If you kept it on the ground, I will run away from there." Raavan got very happy to hear this. He agreed upon this. Shiv gave him his Ling and Raavan took it in his hands and set off to his capital Lankaa.

After giving his Ling to Raavan, Shiv became worried as he did not want to live in Lankaa, so he called his most intelligent son Ganesh and told him everything. Ganesh said - "Father, Do not worry. You don't need to live where you don't want to live. I go and do something for you." So he left.

As you know Raavan was a Braahman, he used to do Sandhyaa every morning and evening. When he was carrying the Ling, he came to south sea shore and the evening fell there. Now he had to do Sandhyaa there. He could not keep the Ling on the ground and there was no place to keep it except the ground, so he looked around and saw a child playing with the sand. He called the boy and asked him to hold the Ling till he finished his Sandhyaa. The boy agreed but asked him to come soon. Raavan strictly warned him to hold it in his hands and not to keep it on the ground. He agreed. So he gave that Ling to the boy and went to the shore to do his Sandhyaa.

Now Raavan took some time to do his Sandhyaa. The boy started shouting, "Where are you? This Ling is very heavy, I can't hold it for long." Raavan also shouted, "I am coming, just hold for a short time more. Do not keep it on the ground." After a while the boy repeated the same sentence and Raavan also repeated the same sentence. Now the boy was getting impatient, so he shouted last time - "I cannot hold it any more, I am keeping it down." Raavan also shouted from there, " I am coming, only a few moments more." and ran to the boy. But as he arrived at the spot he left the boy, the boy had already kept the Ling on the ground and run away.

Raavan filled with rage but could not do anything. He tried his hard but could not lift the Ling from there. It was stuck in the ground. Thus Ganesh Jee saved his father from the embarrassment of his living in Lankaa.