Feral Rage is similar to the Barbarian's Frenzy, although a much less powerful version. Neither damage, attack or the movement speed increases are as great, and Feral Rage does not increase attack speed at all.
However, Feral Rage does give the Druid life steal to his attacks, a much powerful property. The life steal varies with the charges of the skills; the more hits you get in, the more life you will steal. For Skill Level 1, the first hit is 4%, but by three hits, it will now be +12%. A red ball will cirlcle around the Druid, and it will get bigger with each charge, up to a maximum of three (similar to Assassin abilities, but without the finishing moves).