Vaidyanatha - Lord of physicians
In the Kotirudra Samhita of the Shiva Mahapurana, it is said that Ravana the king of the Rakshasas was a great Shivabhakta. He went to Kailasa to perform tapa to please Shiva Bhagawan. But an angry, belligerent person cannot succeed in tapa. After many fruitless years Ravana grew so angry he tried to uproot Mt. Kailasa. Shiva Bhagawan however merely pressed down with his toe and Ravana was squashed under the mountain. Chastened, he decided to try a different way. Ravana had 10 heads and he resolved to cut them off one by one and offer them as a sacrifice. He cut off 9 and was about to do the same for the 10th when Shiva Bhagawan appeared and said enough, I am pleased with your devotion, what do you wish? I will grant it."
Ravana asked for something that would make him immortal and invincible. So Shiva Bhagawan gave him a lingam and told Ravana to take it to his palace in Lanka. He warned him not to put the lingam down even for a second or it would get rooted to the spot. As Ravana took the lingam, his nine severed heads miraculously were restored so happily he set forth back to Lanka. But along the way his eyes suddenly started watering and his nose began dripping. Still he walked on, trying to carry the lingam with one hand and blow his nose with the other. Finally he couldn't take it anymore. (A situation I heartily sympathize with right now :-) He spotted a young cowherd boy and asked him to hold his precious load while he composed himself. The boy (who it turned out was Ganesh Bhagawan who had caused the cold in the first place) took the lingam, set it down and ran off as fast as he could. Ravana tried in vain to pick it up again but it was no good, it was firmly stuck in place. So he had to return home empty-handed.
[Note: As mentioned, this story occurs in the Shiva Mahapurana in the context of Vaidyanatha Jyotirlinga. However I have also heard the same story told about Gokarna tirtha. Supposedly in his futile attempt to pick up the lingam again, Ravana distorted it into the shape of a cows ear (go karna)]
Although Ravana engaged in bhakti and tapa on a monumental scale, it was tainted. He did it for selfish reasons not out of pure love of God. Thus its rewards turned out to be in vain. Because Bhagawan doesn't play favorites with His creations. He impartially alots them the consequences of their karma. For those who do not live a dharmic life no amount of magic objects or weapons or tricks will stave off their inevitable doom.
Vaidyanatha is the supreme bhishhak ( physician). Not only for bodily ailments, He also cures the disease called samsaara. He is therefore called bhava-roga-haraH.
OM VaidyanAthAya namah