From Wiki Grepolis
The hero Jason has been exploring the underworld and managed to bring back a mystic creature, the magic hen. He will allow you to use her powers during the Easter event. If you tend well to her and feed her what she likes she will lay mysterious eggs for you which contain unique rewards.
To get an egg, you have to choose three types of chicken feed. The order in which you place the feed on the bowl does not matter and the same type of chicken feed can be selected more than once.
Next, simply click on the "Feed" button to offer your delicacies to the picky hen. Depending on your combination she will lay an egg which can be either white, bronze, silver, gold or a colored one. If this was the first time you have tried a particular combination, it will be automatically saved in your recipe book.
The egg will then crack open and show you a random reward. You should know that each type of egg has its own set of five possible rewards for which the probabilities to get one differ.
You cannot feed the hen again unless you have collected the reward.
The recipe book automatically saves all combinations you have found and shows which diet leads to which kind of egg. You can also conveniently see here which ingredients are missing for a certain recipe. If you have all the required types of chicken feed you can instantly add them to the feeding bowl just by clicking a button.
Additionally, the recipe book shows you which egg contains which rewards. The first three rewards have a probability of 25% to hatch from an egg. The chance to win the fourth reward is 15%, while the fifth is the rarest with a chance of only 10%.
How to get chicken feed
Every time you complete an island quest, you will receive chicken feed for your hen. The amount of feed depends on how often island quests pop up for you (and therefore on your total number of points). However, the less often island quests appear the more feed you will obtain per quest. Theoretically every player can get up to 12 pieces of food per day. Note that the probabilities to find a certain type of food are not evenly distributed here either. You will find a lot more corn or grass for example than you will find honey.
Of course you can also purchase more food for gold. Please be aware though that the price for each individual food type increases with each purchase. This price increase will be reset every day at midnight for all food types.
Progress and rewards
Next to the hen you see a vertical progress bar which fills up with every egg the hen lays, independent of the color of the egg. As soon as 20 eggs are produced you will receive the services of the merchant for 2 weeks for free. On worlds where heroes are activated you will get 30 coins of war and 30 coins of wisdom instead.
For 40 eggs you will even gain a full culture level! The culture points you have collected during normal game-play will of course remain untouched and still count towards the next level. So you don’t have to wait for a particular moment to bag this reward.