Rill is a wise old water dragon, and we earn him as a hero during the Rill the Wise quest, given by Liang the Dragon Merchant. Rill is also a quest-giver - see lower down this page for a list of quests he offers up. (To see a list of quests given by everyone in the game, go to the CastleVille Legends Quests page.) Rill's Nest takes in Cream and produces XP for you.
Quests given by Rill:
A Thrill for Rill