Heracles was living a good life with his first wife but that moment of happiness was to end very soon. Hera, still angry with Heracles, casted a spell which made him have a moment of madness. It made him kill his wife and his two sons.
The poor hero went to Eurystheus to be purified. Eurystheus told him that if he wants to be purified, he will have to carry 12 tasks.

 1 Kill the Nemean Lion

2 Kill the Lernean Hydra

3 Capture the Golden horned deer

4 Capture the Erymanthian Boar

5 Clean the Augean Stables

6 Kill the Stymphalian Birds

7 Capture the Cretan Bull

8 Capture the Horses of Diomedes

9 Take the Girdle of the Amazon Queen Hippolyte

10 Capture the Cattle of Geryon

11 Take the Golden Apples of the Hesperides

12 Capture Cerberus