hey i know power chords and barre chord but what are some good rock/heavy metal chords?
It depends on what context you use certain chords whether or not they're 'good' for heavy metal. Through experience, I've found the most commonly used chords are E, G, A, C and D in Maj, Min, 7, m7 and 5th forms.

I don't know if that helps.
Heavy Rock/Metal=Power Chords

Another thing I like to do is play major and minor third intervals with an open string pedal tone, like this: