Udupi King has Chikitsa ability which heals a part of your card's stamina in 1st position. This ability works only if the card in 1st position gets hit and the Stamina reduces. Also, Chikitsa ability will not work if the card has retired (i.e. Stamina becomes 0).

E.g. Your 1st card has a Stamina of 3 and an Astr attack reduces its Stamina to 2. Now, Udupi King on its turn gives +1 Stamina to this card and makes it 3 again. Also, Udupi King cannot increase the Stamina to more than 3, i.e. the original Stamina of the card.