Can you please explain me how this class feature actually works ? At which level is it available and what exactly requirements are needed to triger it ? Should i be using a daily rage power at the same time ? thanks in advance
First you have to be 5th level and currently under the effects of a rage power. Then you can expend another rage power and replace that power with Rage Strike. The damage of Rage Strike is dependent on the level of the rage power you are expending for Rage Strike.
So lets say you are 5th level. You have used a 1st level rage power and are now "raging". Now you want to do a Rage Strike. You will then have to mark off your 5th level rage power as used and attack with the Rage Strike power. Since you are expending a 5th level rage power for Rage Strike it will do 4[W]+STR damage if you hit.
The point of Rage Strike is to allow a Barbarian the ability to "Nova" like any other class can without having to change what Rage they are currently using.