So Ravan began his tap, his deep meditations and his worshipping to Lord Shiva to make Lord Shiva happy and to attain the shivling. Pleased after many many years pleased by his dutiful worship and his immense love for Lord Shiva Lord Shiva decided to give him a boon and call him to Kailash and to give him whatever he desires and to bless him in however way ravan wants. So Ravan went to Kailash and he asked for the shivling. The shivling that Raavan wanted had immense powers